Welcome to our Spring 2024 Driving Yield thru Tire Technology Podcast, showcasing all the latest new tire products that not only Increase Yield, but also Improve Productivity, and Reduce Fuel – all straight from the manufacturer’s representatives!
Plus, check out our new format, enabling you to listen to only the specific product you are interested in- a must listen to if you are thinking about making a major purchase.
The following “Driving Yield thru Tire Technology” Podcast is brought to you by:
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AG TIRE TALK KEY TAKEAWAYS
QUESTION: Why is a tire, when run at slower speed, able to carry same load at lower air pressure?
MICHELIN: “The structural integrity of the tire is being compromised, more often as speed increases, and more significantly as air pressure decreases.”
ASCENSO: “The central subject for this question has to do with the law of coefficient of friction- the faster an object moves against another object the more heat is built up, and all tire folks know that heat is the worst enemy of a tire.”
MAXAM: “If the right inflation pressure based on the axle load for a given speed is set, the tire is designed to deflect and absorb the heat, delivering performance and endurance.”
YOKOHAMA TWS: “As tire materials and design technology has improved, the tire international standards organization has recently introduced additional load values when speed is reduced.”
BKT: “At Field Speeds, 5-10 mph, tires can be run with less air pressure to get a longer and wider footprint to better distribute the weight of the tractor and/or implements. This allows for better traction (fuel economy) and less ground-bearing pressure (soil compaction).
PRECISION INFLATION: “By changing tire pressures on the go with CTIS & CFO, tire pressures in sprayer application can be reduced up to 49%.”
Yokohama TWS
Chris Neidert: AG Marketing, Training & Development Manager for Trelleborg & Mitas Tires – North America
Let’s get a little technical!
Deflection
Pneumatic tires are designed to be flexible and adaptable to the application in which they are operating. Because of the weight they bear, tires sidewalls bulge under load and their treads flatten to increase the contact area and traction as they roll.
This sidewall bulge results in a dimensional difference between the tire’s “unloaded” radius (i.e., between the center of the axle and the top of the tire) and its “loaded” radius (between the center of the axle and the road) called “Static Loaded Radius” (SLR). Engineers call this radial deflection.
Increasing Speed = Higher Frequency Shape Change
When a tire travels on the road or field it rotates and constantly changes its shape between the unloaded radius and the loaded radius form. Increasing the vehicle speed will increase the frequency of this change and cause the tires to deflect at a faster rate. This is an important point to remember to understand the internal chemistry of the tire components.
Hysteresis is Amount of Energy Lost
This involves a term called “hysteresis”. Hysteresis is the percent of energy loss per each deformation. Hysteresis results from friction happening inside the rubber which creates heat build-up. The heat build-up in the rubber is measured as the temperature increases from hysteresis. You want to keep the amount of hysteresis low.
With that being written, when a tire is rotating at a slower speed, the deflection cycle is slower allowing the tire more time to cool down when it’s in the less deflected position. In other words, the heat is generated on the bottom part of the tire and the upper portion of the tire cools down. The faster this cycle, the less time the upper part of the tire has to cool down.
Increasing Speed = More PSI Required
Each tire size uses a certain air pressure to carry a specific load at a specific speed. Conversely, when the tire’s speed increases, as in moving from the field to the road, and the air pressure is not increased, the speed of deflection movement increases and the amount of deflection increases. This will build up additional heat in the tire, reducing tire life and possibly creating a tire failure. Tire air pressure must be increased when speed is increased.
Increased Load = More PSI Required
The same will hold true for a load increase. If no air pressure adjustment is made, the amount of deflection increases. Heat buildup happens. Tire failure is possible and tire life is reduced. Tire air pressure must be increased to reduce that deflection. Higher inflation pressure results in a more “stiffer” tire sidewall, less deflection, and less heat buildup.
Road PSI & Field PSI Optimizes Performance
We at Trelleborg & Mitas have always said the ideal situation is to run one air pressure in the field and another air pressure on the road. This will give optimum tire performance and tire life. A Central Tire Inflation System or (CTIS) would accommodate this recommendation with its ability to change air pressure on the fly.
OLD Load Speed Tables
When IF technology was first introduced the decision was made to make the load tables as easy as possible to use. Hence, the load table was designed that no matter what speed you were traveling, one air pressure was recommended. You can see in the below load table, speed did not change on any air pressure recommendations. One air pressure would carry the load no matter the speed. Example – If you needed to carry 18,850 lbs. you would need to run 26 PSI whether your speed was 40 mph or 5 mph which is shown as Field Service Speed
NEW Load Speed Tables
As tire materials and design technology has improved, the tire international standards organization has recently introduced additional load values when speed is reduced. Tires built with IF and VF technology have new expanded load tables.
In our example below, we have the exact same tire but with an expanded load table. The tire load will be the same, 18,850 lbs. Now we can better suggest an air pressure based on the application. We will use an application of doing some slow speed work (5 mph) in a low torque (LT) application.
We can find the 5 mph LT speed. Go across until we find the load 18,850 lbs. We will need to approximate since 18,850 is not exactly shown. Going up the table until we intersect the psi row, we would suggest 20 psi. Quite an air pressure reduction from the 26 psi we would be recommending with the old table.
The reduced air pressure will increase the size of the tire’s footprint, reducing the ground pressure, reducing compaction, and improving yield. Tire performance will be better for the grower.
Michelin Ag
David Graden: Operational Market Manager – Agriculture
Higher Speed = More Air Pressure Required
I would like to start with rephrasing this question to, “Why does a tire require more air pressure at faster speeds?” As a tire rolls, the perfectly circular shape of that tire transforms. The bottom flattens out and rolls over bumps and through divots. As the tire rolls faster, the circular shape transforms to more of an oval or oblong shape. This transformation creates a couple of concerns.
Tire Structural Integrity
First, the structural integrity of the tire is being compromised, more often as speed increases, and more significantly as air pressure decreases. You would think lower air pressure at higher speeds would create a smooth ride; however, it also creates bouncing, which can overload a tire each time downward pressure is applied.
As structural integrity of a tire is compromised more often with higher speed, and the casing is more deflected at lower air pressure, heat increases. In severe cases, underinflated tires at high speeds will cause that tire to fail from the inside out. The radial belts will separate, carcass plies will break and pull apart and the rubber will actually begin to melt.
Stability
The second concern is stability of the vehicle. At lower speeds and air pressures, an operator can easily maneuver machinery over bumpy terrain and around obstacles. At higher speeds and lower air pressures, however, it becomes much more difficult for the operator to manage these tasks. Think about a high clearance sprayer. As this top-heavy machine makes a sharp turn, the tires will flex and the machines weight will shift to one side, overloading the tires on that side and possibly failing. If the tires are set to proper inflation pressures, they will be able to handle the weight shift and limit the leaning of this machine to one side.
Slower Speed = More Weight Capacity
Why can a tire carry more load at lower speeds and air pressures? As I mentioned above, a tire deforms more often at higher speeds, creating more heat- the worst enemy of a tire. At lower speeds, the opposite is true, and the structural integrity is better preserved. Simply put, this lack of stress on the tire carcass allows it to carry more load.
Central Tire Inflation System Optimizes Performance
When we consider the daily activities of most farm machines, they aren’t always operated at the same speed or load. This is exactly where Michelin’s PTG, Central Tire Inflation Systems, comes into the picture. We know, for a fact, machines operate much more efficiently at lower air pressures, in the field, and are more stable at higher pressures, while traveling down the road at higher speeds. Unfortunately, I’ve never met a machine operator willing to stop what he/she is doing to change air pressures before each of these activities.
With PTG, Central Tire Inflation Systems, there is no need to manually change air pressures, or even stop the machine, for that matter. With the push of a button, a machine operator can change tire pressures for up to 2 axles and an implement! This technology now enables producers to gain full operational efficiency of their machinery. Full operational efficiency means maximum traction, floatation, fuel efficiency, stability, and rider comfort.
CFO Provides Additional Live Load Capacity
Finally, several years ago, Michelin was one of the first manufacturers to begin designating harvester and sprayer tires with CFO (Cyclical Field Operation) Load Bonus- enabling even heavier loads than standard, at specified slow speeds, for a limited distance.
Look at this Michelin Spraybib, as an example: VF380/90R46 173D CFO (Cyclic Field Operation)
As I mentioned earlier, typically, a tire can carry heavier loads at slower speeds, so why does this example not follow that same rule of thought?
Since the sprayer is getting lighter as herbicide is used, we only need the CFO Tire to carry the load for 1 mile– limiting the amount of times tire deforms. Hence, we can increase the load more than standard temporarily.
BKT USA, Inc.
Dave Paulk: Manager Field Technical Services
At field speeds, 5-10 mph, tires can be run with less air pressure to get a longer and wider footprint to better distribute the weight of the tractor and/or implements. This allows for better traction (fuel economy) and less ground-bearing pressure (soil compaction).
As speeds increase, the load carrying capacity of the tire decreases. The low air pressures that can be used at field speeds are not the same air pressures that should be used at highway speeds. Higher air pressure must be used to carry the load at a faster speed. The higher air pressures create a smaller footprint for lower rolling resistance on the road.
Using a Load and Index Chart for the tires used is helpful to eliminate possibilities of damaging the tire by overloading and underinflation. The Load and Index Chart gives weight carrying capacities at different speeds and air pressures. Less air pressure equals less soil compaction in the field. As noted, the air pressures must go up for road transport at higher speeds. Currently, to accomplish this, one must reduce air pressure in the field and inflate the tires before taking the tractor on the road. An air compressor is needed to do this. Central Tire Inflation Systems (CTIS) are being developed and will be built into the tractor to perform this function. Air pressures can be reduced in the field and pressures can be increased as needed for the road. This can reduce compaction and increase fuel economy in the field and minimize tire failures on the road. Running a tire with low air pressures at highway speeds creates heat buildup in the tire. It can’t dissipate the heat quick enough over long distances and can lead to ply gap turnup and sidewall separations. An example of a Load and Index Chart is shown. This is for a 480/80R50 159 A8/B.
Standard tires can be used with less air pressure at slower speeds. With the use of IF and VF tires, air pressures can be reduced even more at field speeds. A VF tire will carry 40% more weight at the same air pressure as a standard tire of the same size. At slower speeds, air pressure can be reduced even more to minimize compaction.
As stated, lower air pressures can be used at slower speeds if enough air is used to carry the weight of the tractor and equipment. Proper air pressure for the weight carried (whatever that may be) is required so that the tires are not overloaded. There are times when low air pressure can’t be used. Overloading tires will lead to bead and sidewall failures in the field. An example is sprayers, since at times they run at faster field speeds than tractors and start loaded with liquid. Another example is using a 16-row planter on a 3-point hitch. With the planter down at field speed, air pressure can be reduced. When it gets to the end of the row, the planter must be picked up to turn. This is a lot of weight on the tires with low air pressure. Worst case scenarios should be considered when deciding the correct air pressure for the application.
IF-CFO and VF-CFO tires are used in cyclic applications such as grain carts and combines. CFO is an abbreviation for “Cyclic Field Operation”. These applications start with the hoppers or carts empty and build up weight over time. When they are full, they are dumped and start empty again. Because of this, the weight of the machine is constantly changing. The load is cyclic. For these applications, load bonuses are given at slow speeds (field speeds at 5-10 mph and 10-20 mph) for a specified distance. An example is shown of a 1250/50R32 201B IF-CFO tire used in this application. At 5-10 mph, this tire has a 55% load bonus without changing air pressures. At 10-20 mph, the tires have a 30% load bonus. These factors are not to be used when considering air pressures for tractors. Tractors generally have a constant weight and are not cyclic.
Although sprayers may be considered cyclic, they are cyclic in reverse. Sprayers start heavy and full. As they use the liquid in the tanks, they get lighter. Instead of going from light to heavy like combines and grain carts, they go from heavy to light.
The faster the speed a tire travels, the less weight carrying capacity it has. The slower the speed, the more weight carrying capacity it has. This is true for all tires. This can be seen in the Load Capacity chart above. When deciding how much air pressure to run, always look at the worst-case scenario and use that to decide.
Ascenso Tires North America
Nick Phillippi: Product Manager / Technical Support North America
I am not a physicist, and the deep mathematical calculations and presentations are for others to give. But as a tire person, the central subject for this question has to do with the law of coefficient of friction. The faster an object moves against another object the more heat is built up, and all tire folks know that heat is the worst enemy of a tire.
The load, air, speed ratings of tire are set based on maximum speed, maximum load and maximum air. The slower the operation is, as compared to the maximum speed rating of the tire, the tire handles more weight safely. Now, as always, all tire data is based on (1) tire in new condition, (2) Wheel in new condition, (3) Equipment in new condition, (4) Surface flat and free of obstacles, (5) No extreme ambient or surface temperature. In short, the end user and tire service professional need to be aware of any of these factors that may impact the ability of the tire to operate safely.
VF tires are being used more and more in lower speed or variable speed settings, requiring the new load charts to give direction on capacity at lower speeds and in intermittent speeds/loads. As more and more VF tires are produced and more data is available in the market on performance, along with more testing being conducted, it has given reason to create the new charts and to be sure existing and past load index charts were accurate.
Central Inflation Systems are an absolute necessity to get tires operating at the proper and lowest pressure possible to minimize compaction and meet optimum Fuel vs Slip. Although CTIS today only uses the measured worst case scenario weight to adjust the air in the tire from Road to Field, not taking into consideration live load changes, it is so much better than any chance producers will adjust pressure from Field to Road, or even between pieces of equipment.
Maxam Tire International
Greg W. Gilland: Vice President Global Agriculture
Radial Superiority
In a previous article, we covered the differences between radial and bias tire construction. In summary, the primary difference between radial tires and bias ply tires is in the tire carcass, as well as the material construction of the tire.
The key difference between the two types of construction is how the radial tire uses the “single” radial casing as a “spring mechanism” that pushes the working belts onto the working surface, ensuring a uniform “contact patch” or contact area for the tire tread. This delivers both the necessary traction and friction, carrying the required load in any direction under power. The improved footprint and traction delivered by radial tires has accelerated the adoption of radial tires as the primary construction type on both new and older agricultural equipment. With the performance advantage created by the radial casing, the air pressure in the chamber takes on a larger part of the load carrying capacity, moving from 60% to 80% of the axle load carrying capability:
The radial advantage is delivered by the air pressure in the inner chamber that fluctuates per the given axle load, whether mounted as a single tire, dual, or triple fitment. All tires are a compromise, as well between load and speed, radial casings and rubber compounds have been enhanced over time. This allows the tires to operate at higher speeds and absorb the heat generated by the friction of the road versus a given axle load. Over the last 20 years, we have seen radial tires evolve from the traditional dual speed rating of A8 = 25 MPH / B = 30 MPH to a “D” Rating = 40 MPH capability as the market demands and requires faster capabilities. In every case, the rubber compounds, as well as casing materials must be engineered to not only carry the loads but have the endurance to deflect or flex up/down as the tire absorbs the energy generated by both load and speed.
Heat is Biggest Threat to Tire Failure
The biggest threat to tire failure is excessive heat generation caused by overload or overspeed. Overload occurs when tires are underinflated for the axle load. Whereas overspeed failures occur when tires are either overloaded (not enough air pressure) for the rated speed or operated above their speed rating, increasing the friction coefficient of the tire rubber compounds. As a rule, the key to load bearing capability is the correlation between the actual weight being carried and the machinery speed. If the tire inflation pressure is set to the right inflation pressure based on the axle load for a given speed, the tire is designed to deflect and absorb the heat, delivering performance and endurance.
Slower Speed = More Weight Capacity
If you slow the machinery speed without changing the air pressure in the chamber (already at a higher pressure), the air in the chamber allows for heavier loads to be carried as heat generation caused by the friction or tire flexing is reduced dramatically, this reduces the heat in the inner chamber that is normally generated between the air molecules. In all cases, tire manufacturers abide by industry standards that reference principles of temperature and air pressure to determine the optimal speed, weight bearing capability, and resulting heat generation for a given tire size air chamber.
If you choose to lower the air pressure, then the load being carried must be measured so that the correct lower air pressure for that given speed is identified, thus allowing the air molecules in the chamber to heat up without overheating the tire.
IF / VF Advantage
The advent of IF or VF Technology has allowed some of the above rules to be re-written, transferring back to the casing materials a greater share of the load carrying technology. For agricultural tires, whether using IF or VF technology tires, farmers can either significantly lower air pressure without compromising the carrying capacity of the tire or increase the weight carried with the same tire footprint (same gross flat plate). Both technologies allow farmers to achieve better yields or greater productivity in the field with heavier or faster machinery. Specifically, VF tire technology construction uses different casing and rubber materials to achieve the benefits mentioned earlier, by delivering the product solutions below in comparison to the standard tire construction:
The growing use of “On-Board” Tire Inflation or Central Inflation Systems technology has created a feedback loop adjustment tool supplied by the machinery that is connected to the tires. This includes the capability to inflate or deflate the tires as needed based on the required speed or working axle load demand. On-board or Central tire inflation systems receive data from either an RFID or sensor tag, located by wheel position on the machinery and gives the operator the capability to adjust the tire inflation pressure in real time and as needed without having to stop the machinery. Whether working in the field at slow speeds or transporting the machinery (roading) from field to field at higher speeds, the ability to adjust the tire air pressures as needed can ensure the following benefits:
Precision Inflation Systems
Ken Brodbeck: VP of Technology
Why Can a Tire Carry More Load at Slower Speeds?
Usually, the tire’s toughest condition is being run at its maximum load and speed.
A tire’s tread and sidewalls flex rolling through the footprint. Internal friction from flexing creates heat. Tire temperatures can easily go above 200 degrees F and start to cause the rubber to revert or become gooey. Then the tire can fail.
The slower the tire goes, the less heat is generated, and a higher load can be carried without overheating.
Michelin now offers higher cyclic loads for sprayer tires up to 20 mph field speeds.
Example:
A VF 420/95R50 179D/175E:
A 1200 gallon sprayer with 28% fertilizer has the following loads per tire in road & field configuration.
NO CENTRAL TIRE INFLATION SYSTEM
Roading, 40 mph loads (Folded Boom)
Front lbs. psi Rear lbs. psi
13,400 39 12,000 30
Field, 40 mph loads, (Unfolded Boom)
Front lbs. psi Rear lbs. psi
10,200 25 15,200 47
Without changing tire pressure, the required psi is
WITH CENTRAL TIRE INFLATION SYSTEM
By changing tire pressures on the go with CTIS, up to 20 mph, air pressure can be reduced!
Field, CFO 20 mph loads (Unfolded Boom)
Front lbs. psi Rear lbs. psi
10,200 20 15,200 39
Changing tire pressure with CTIS, accommodating load and speed change, the required psi is
By changing tire pressures on the go with CTIS & CFO, Up to 20 mph, front tires only need 20 psi.
UP TO 49% PSI Decrease
No CTIS & No CFO > Required psi, F = 39 psi & R= 47 psi
With CTIS & CFO, F= 20 psi & R= 39 psi
PSI Reduction of, F= -19 psi & R= -8 psi
Mindful, air pressure reduction directly correlates to reduced soil compaction, using slower speed tables with CTIS provides:
All information is provided in this blog solely to provoke thought. All deductions made from information on this site must be confirmed by Certified Ag Tire Dealer & Tire Manufacturer before use. Ag Tire Talk does not recommend anyone conduct tire service work with exception of Certified Ag Tire Dealer Professionals.
]]>AG TIRE TALK KEY TAKEAWAYS
MICHELIN: There are three primary options when it comes to lug angles of large Ag tires. Typical Ag tires are designed with a 45-degree lug angle; however, in the 1950s, Firestone introduced the 23-degree lug angle, and in the early 2000’s, a new hybrid lug design was also introduced to the market.
YOKOHAMA TWS: The 45-degree lug angle is the better choice for farming on hillsides. This is because this lug angle will help the operator keep the equipment in the rows. The lower angle lug tires contribute to equipment side slippage or dog-tracking. This can let the equipment run over existing crops.
MAXAM: IF and VF technology tires perform at top-tier rates when coupled with the 45° lug tread designs, delivering the load, speed, heat resistance, and endurance that is demanded both now and for the years to come.
BKT: Lower degree angles seem to do well in the field but do not handle the roads as well.
PRECISION INFLATION: Lower bar angles provide more traction, 23 degree, N. America. Higher bar angles, 45 degree, wear longer in high road usage, like Europe.
ASCENSO: Why are 45-degree lugs on R1- R1W tires becoming dominant? Probably because it seems to meet in the sweet spot of traction and ride and gives a good net-to-void ratio for wear.
YOKOHAMA OFF-HIGHWAY TIRES AMERICA: The continuous angle tractor tire lug dates back to the era of steel wheels. It’s an enduring design, but some tire manufacturers have innovated more effective patterns that update tire technology to better serve today’s modern machinery.
Yokohama TWS
Chris Neidert: AG Marketing, Training and Development Manager for Trelleborg & Mitas Tires – North America
Tread Design Differences
Let’s establish some understanding of what we are talking about with the term “lug angle”. 45-degree and 23-degree lug angles are the most common. The number comes from the angle of the lug in reference to the horizontal. As seen in the graphics below, a typical 23-degree tread lug is usually flatter, or more towards the horizontal and the 45-degree lug will point more towards the vertical.
Why does continuous angle 45-Degree Lug optimize both Field & Road Performance?
Trelleborg and Mitas have always maintained the preference of a 45-degree lug angle is the best for both worlds. In field performance and on-road performance. This tread design has a European influence since European farmers do a lot of roading. This is due to the smaller farms in Europe and the need to travel from field to field on the “road”. This design offers good field performance and very good smooth ride on the road. Our feeling is with lower degree lugs, meaning the lugs being more angled towards the horizontal, a washboard effect is created. The effect contributes to a rougher ride.
What are benefits of Lower Degree/Higher Degree Angle?
Dry Soil operation – The lower degree lug angle may lend itself to better traction in dry soil. Not sure how many areas of the country, continually operate in dry soil. If the grower does operate in that type of soil, chances are they will still need to road the tractor to get to their next field. The washboard ride will come into play.
Sidehill operation – the 45-degree lug angle is the better choice for farming on hillsides. This is because this lug angle will help the operator keep the equipment in the rows. The lower angle lug tires contribute to equipment side slippage or dog-tracking. This can let the equipment run over existing crops.
Traction – 45-degree lug tires have wider lug spacing. This will enable the tire to clean out when operating in wet, sticky, and muddy conditions. The lower lug angle tires tend to pack up with mud and debris in these conditions. Traction will be compromised.
Poor Road Performance/Improved Road Performance
Continuing our theme on the 45-degree lug angle is the best of both worlds (in field and on road), the higher the lug angle the better the ride. As the lug angle moves more towards the vertical, the lug face will stay in contact with the road longer as the tire moves through the footprint. This longer lug contact will provide a smooth transition from lug face to lug face. This will make for a smoother ride than a lower angled tire- the lower lug angle tire will have gaps between lug contact with the road, creating that washboard effect and a rougher ride.
When do you recommend departure from traditional R-1/R-1W Design?
What tread design alternative do you recommend?
Many applications do not require the aggressive and deep tread depths that are characteristic of the R-1 & R-1W designs- examples are roadside mowing and snow removal. I’m sure we have all been traveling on the freeways and the roads outside of our town. Those tractors we see doing that mowing are usually operating in grass. Maybe taller grass than our yards but grass none the less. The tread pattern on the left is ideal for that application. Shallower tread depth and more of an all-season design. It lends itself to less ground disturbance, longer wear and still providing the needed traction to get the job done. Depending on where you live, snow removal is another perfect application for this tread design.
Maxam Tire International
Greg W. Gilland: Vice President Global Agriculture
When reviewing tire tread designs for traction across various applications and surface conditions, the best traction available for any operation in softer soils or cropped fields would be a flat or horizontal traction bar like a military tank tread or tracked dozer. The horizontal traction bar effect on ride, fuel efficiency, and slip rates quickly moved the agricultural industry to the traditional R-1 chevron design. Early tire tread designs adopted the 23° lug angle that improved the ride while ensuring good field traction and improved fuel efficiency.
The 45° lug concept was initiated by tire manufacturers in Europe as the tractor applications were significantly different than in North America. European applications demanded more time on the road, transporting to the market, or simply moving from the farm to the field in many cases towing implements or cargo. This application requirement in Europe pushed tire manufacturers to adopt the 45° angle chevron design for all powered machinery using R-1, R-1W, R-2, and even R-4 agro-industrial products. This design has become the industry standard as all agricultural tire manufacturers have adopted the 45° lug angle as the optimal design for core farming with both radial and bias ply constructed tires. From the smallest below 65 horsepower machinery to the latest +700 horsepower machinery rolling off the OEM production lines, the 45° lug radial chevron tread from R-1 to R-4’s is leading the product performance expectation to deliver the value that farmers and growers are seeking in their tires.
The MAXAM radial agricultural product offering is centered on our AGRIXTRA tread design that is uniformly standardized across all our standard and VF R-1/R-1W tires- the 45° lug bar allows our tires to deliver improved traction, stability, endurance, and improved wear. Listed below are the key elements of our tread design and the benefits of our engineered features:
Beyond the field work environment that requires the efficient transmission of the machine engine torque and flotation, the growing market evolution is requiring that agricultural tires deliver the performance traditionally expected of automobile as crops are harvested and brought to market by a tractor. As agricultural machinery continues to grow in weight, engine horsepower, and transmitted torque, the tread design coupled with the growing need for IF & VF technology is rewriting the rules. This gives the structural components of the tire a larger impact on the performance and value the tire must deliver. Therefore, IF and VF technology tires perform at top-tier rates when coupled with the 45° lug tread designs, delivering the load, speed, heat resistance, and endurance that is demanded both now and for the years to come.
Beyond the use of the 45° Lug design with or without improved materials such as IF or VF construction, we are seeing more modified tread designs that increase the contact area of the tires. By increasing the width of the lugs or by reducing the void to lug ratio areas by adding more lugs in the traditional void area, IF and VF technology can increase the contact patch. This is specifically occurring in agro-industrial applications that may include the use of utility tractors, mower tractors, backhoes, compact wheel loaders, and telehandlers. We are seeing the evolution of the R-1 tread design beyond the 45° lug concept from the traditional chevron tread design to a multi-purpose or MPT tread design that emphasizes more rubber contact or additional lugs in the void areas. The goal of these modern designs is to deliver just enough traction to ensure the soil conditions can be met while delivering more contact area. This results in a higher tread endurance required of harder or more demanding surfaces historically reserved for more robust construction application-oriented tires or tread designs. What is clear is that the concept of the 45° lug on R-1 to R-4 tires even with more lugs like the evolving MPT tread concept has successfully met the market need for traction, constant contact, and machine productivity.
MAXAM will be developing additional VF and MPT tires in the coming years to meet the evolving global demand for higher load, platform, or market technological changes, employing our new Ecopoint3 rubber compound technology to rewrite the tire endurance rules and deliver value-centered products that will exceed OEM and farmer expectations.
Michelin Ag
David Graden: Operational Market Manager – Agriculture
There are three primary options when it comes to lug angles of large Ag tires. Typical Ag tires are designed with a 45-degree lug angle; however, in the 1950s, Firestone introduced the 23-degree lug angle, and in the early 2000’s, a new hybrid lug design was also introduced to the market. There is also an ongoing argument of which is better; Firestone’s 23-degree or Michelin’s 45-degree. In short, it really all depends on the application and soil conditions.
Let’s start with the benefits of a 23-degree lug design. Imagine, if you will, an Ag tire with 23-degree lug angles. In general, the lug angle takes up less linear (front to rear) space than a 45-degree angle. Therefore, more lugs can fit around the tire, which means it is possible for more biting edges to come into contact with the soil. In perfect conditions (i.e. flat land and dry soil), this could be a good fit for you. Unfortunately, it seems these conditions are rarely the case for most farmers across North America.
Let’s now look at the 45-degree lug angle and understand why this is the standard for most Ag tires. It’s true that with this lug angle, less lugs can fit around the tire, leading to fewer individual biting edges. However, each lug is longer and continues to circle around the tire a bit more than the 23-degree lug. This introduces 4 benefits: smoother ride, stubble resistance, better mud evacuation in less-than-ideal conditions and greater stability and traction on slopes.
Over the next 10+ years, we have seen many new and innovative hybrid lug designs hit the market. In fact, Michelin has developed a few of its own, but for very specific applications. One example is the Michelin Roadbib tire. Whereas this tire still isn’t a good fit for high torque applications and all soil conditions, it is an excellent design for 80% road travel (like manure spreading contractors) and silage packing. Additional benefits to this design are improved fuel economy on the road, higher speed index, very long tread life and an impressive smooth ride. All of these are a result of more rubber contact with the ground/road, which causes much less friction and movement in the rubber.
In summary, farming conditions from year to year are not predictable. Tires are a very large investment and detrimental to the performance and overall efficiency of the machine. The 45-degree lug design is the best option for most conditions. Add the Michelin standard R1W lug depth and you’ve covered all possible soil conditions an operator will have to work through. If you’re a contractor and spend most of your time on the road, between farms, consider a hybrid lug design for improved fuel economy and speed.
BKT USA, Inc.
Dave Paulk: Manager Field Technical Services
Farmers must travel greater distances on highways to get from farm to farm. Tractors have become heavier and travel at faster speeds than in years gone by. Farm equipment such as planters, cultivators, etc. are heavier and higher horsepower tractors are needed. As the equipment and uses of equipment have changed, farm tires and tire technologies have changed to accommodate the uses.
Some of the older farm tire technologies don’t seem to stand up to today’s demands as well since more on the road use is required. A tire and a tread pattern must be used that is good in the field and does a good job when highway travel is needed.
The 45-degree angle tread pattern is a good fit for field and highway use. This tread pattern runs well on the highway as the curved center lugs allow even wear and good contact with the road. This helps by minimizing the uneven wear caused by highway use. This tire allows a comfortable ride on the road.
The 45-degree angle is good in the field as it cleans out well and provides good traction for pulling heavy implements. With the correct air pressure, it gives a good footprint to minimize soil compaction.
When transitioning from the field to road, the 45-degree angle lug is a good tread pattern for both uses.
Lower degree angles seem to do well in the field but do not handle the roads as well. Higher degree angles are somewhat better for highway use but give up some traction in the field. The 45-degree angle tire seems to be a good fit between high angle and low angle lugs and works well in both applications.
Running on the road is a necessity to move equipment from one field to another. Unfortunately, the more farm tires are used on the highway, the faster they wear out. Starting and stopping and the contour of the road are contributing factors for causing tire wear on the road. Although the tread rubber in most farm tires is compounded to improve tire life when running on roads, their main purpose is to perform well in the field.
The R1/R1-W design provides good traction in the field. The lugs generally clean out well because of the lug design. When the tractor is used in dry dirt and/or mainly on the highway where traction isn’t a huge concern, a user may look at a hybrid tire to get better tread wear and prolonged tire life. Hybrid tires (such as a BKT IT696 or IT697) are a good option for heavy highway use. They do provide a moderate amount of traction in the field, but don’t clean out as well as an R1/R-1W design in wet dirt. Because they have a blockier tread design and more tread rubber on the road, they are a good alternative for highway use.
Ascenso Tires North America
Nick Phillippi
Why does continuous angle 45-Degree Lug optimize both Field & Road Performance? Not sure it really does. I think it has been seen that way and does perform well if you say we need to decide on one thing for all vehicles, but that shouldn’t be done.
On a 45-Degree Lug, the longer length of the bar lug, along with percentage of center line overlap, all play into improved ride and wear, just as much as the angle.
On the other hand, Lower Bar Lug Angle tires provide more forward and reverse traction; however, road performance is poor.
Specific Applications like sprayers, carts, and planting tractors benefit from more broken hybrid tread patterns- the more roading, the greater the benefit. Ascenso provides the following hybrid tires: VDR901, MDR1000, and UTR240.
A tire design is usually built using a triangle matrix where TRACTION, RIDE, and WEAR are the key elements of design consideration and the more you prioritize one the more the others suffer.
Why is 45-degree lugs on R1- R1W tires becoming dominant? Probably because it seems to meet in the sweet spot of traction and ride and gives a good net-to-void ratio for wear.
Is this always true? That all depends on the use!
The less the angle, the better the forward traction. Remember when things were slow and forward traction was it?
Zero degrees in soft soil is the highest traction per square inch in both forward and reverse, but oh what a ride on the road! Plus, you have no lateral traction.
I don’t believe 45 degrees should be thought of as the best to optimize both field and road as much as most think.
The challenge is always what is the need 90 % of the time?
I think the market is putting too much into the 10% of the time on most vehicles that are in use. A sprayer, cart, or a planter or silage packer tractor, as most farmers today have task-specific vehicles, should consider the broken tread designs. Any time you add center ride pattern tread you will have much better road wear and driver comfort and handling.
Yokohama Off-Highway Tires America, Inc.
James Crouch, National Product Manager—Agriculture and Forestry
The continuous angle tractor tire lug dates back to the era of steel wheels. It’s an enduring design, but some tire manufacturers have innovated more effective patterns that update tire technology to better serve today’s modern machinery.
One of the most basic innovations has been a multi-angle lug, which uses a shallower angle along the edges of the tread to maximize traction and a sharper angle—as well as overlaps and wider nose designs—in the centerline to reduce wear and improve road handling characteristics.
With our Alliance brand of farm tires, Yokohama Off-Highway Tires has taken many of our R-1 designs to the next level by breaking the curved lug into blocks. That creates more biting edges for traction and allows us to increase the surface-to-void ratio toward the centerline for even better roading, while maximizing void along the edges for grip and self-cleaning. You’ll see this “hybrid tread” pattern on tires like our Alliance 363 and 550 R-1 radials, and modified versions on a wide range of I-2s and I-3s, including our flotation radials and implement tires.
Not surprisingly, there’s a lot of engineering and construction skill that goes into hybrid tread. Too much movement would create excess heat and cracking, so we’ve innovated tie-bars, lug angles and multi-step designs to create the most high-performance tread patterns R-1 tires have ever seen. After all, we left steel wheels behind 100 years ago. It’s high time our tread patterns start to catch up with all the other innovations we’ve made in tires over the past several decades.
Precision Inflation Systems
Ken Brodbeck: VP of Technology
What is the Best Tread Pattern?
First, there are 3 Traction Ag Patterns.
R-1: For general traction work.
R-1W: Like R-1, but with extra tread depth for longer life.
R-2: Rice and Cane farming, twice the R-1 tread depth.
Most tire companies make several versions of the R-1 and R-1W in various tread patterns. Each company claims their tire is the best for you!
With over 40 years as an Ag. tire engineer, these are the general basics:
3. Curved bars start with a high bar angle in the center and then move to a lower angle out to the shoulder. Both low and higher bar angle in the same pattern.
4. Center Rib For high pressure sprayer tires for better road wear.
And if you really want the best tread for BOTH FIELD TRACTION and ROAD TRANSPORT, YOU NEED A TIRE WITH THIS FOOTPRINT!
AND, CTIS (CENTRAL TIRE INFLATION SYSTEM)
CTIS Optimizes the Field Footprint:
CTIS Optimizes the Road Footprint:
CTIS makes Every Tread Pattern the BEST for both FIELD AND ROAD!!
All information is provided in this blog solely to provoke thought. All deductions made from information on this site must be confirmed by Certified Ag Tire Dealer & Tire Manufacturer before use. Ag Tire Talk does not recommend anyone conduct tire service work with exception of Certified Ag Tire Dealer Professionals.
]]>The following is brought to you by:
Michelin Ag
David Graden: Global Account Manager – Agriculture
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]]>Welcome to our Fall 2023 Driving Yield thru Tire Technology Podcast, showcasing all the latest new tire products that not only Increase Yield, but also Improve Productivity, and Reduce Fuel – all straight from the manufacturer’s representatives!
Plus, check out our new format, enabling you to listen to only the specific product you are interested in- a must listen to if you are thinking about making a major purchase.
The following “Driving Yield thru Tire Technology” Podcast is brought to you by:
]]>AG TIRE TALK KEY TAKEAWAYS
MAXAM: “The development of IF (increased flexion) and VF (very increased flexion) technology is allowing working air pressures to be lowered significantly delivering improved performance and better crop yields.”
BKT: “There are definite advantages in using IF/VF tires and applications where they work and perform much better than standard tires.”
YOKOHAMA OFF HIGHWAY TIRES AMERICA: “That’s because IF and VF Tires can help farmers reduce compaction force on their soils by 20 to 40%, or carry higher loads than conventional radials without increasing compaction.”
MICHELIN: “Independent studies conducted by Harper Adams University and University of Illinois, Urbana-Champaign, both concluded using Michelin (IF/VF) tires, at properly recommended field air pressures, will produce up to an additional 4.31% yield.
YOKOHAMA TWS: “How can tires with IF/VF Technology carry the same load with less air pressure? The answer is because the sidewalls have been redesigned to carry some of the load, whereas standard radial tires use the air pressure to carry the entire load.”
Maxam Tire International
Greg W. Gilland: Vice President Global Agriculture
On average, agricultural tires tend to operate between +16-20 psi for MFWD or 4WD tractors working in the field, about +25 PSI for combine harvesters, and above +60 PSI on self-propelled sprayers. The development of IF (increased flexion) and VF (very increased flexion) technology is allowing working air pressures to be lowered significantly delivering improved performance and better crop yields. The structural design and capability of modern tires impacts how much air pressure is required to carry the intended axle load.
All radial tire casing structures from nylon to steel chords with its inherent rubber layers only carry 20% of the actual intended load with the compressed air accounting for 80% of the carrying capacity. This is true in any radial tire application, from passenger vehicle tires to the largest giant OTR mining tires. The advent of IF & VF technology is rewriting the rules by giving the structural components a larger impact on the carrying capacity. Transferring the axle load carrying responsibility away from the compressed air and increasing the weight-bearing function back to both the casing and rubber materials. IF and VF technology tires are evolved products that use improved rubber compounds and higher tensile strength cables or chords to achieve the load, speed, heat resistance, and endurance that can be demanded in their work applications or conditions.
The below visual examples of a 520/85R42 on a harvester (dualled application) drive or front axle display the effect of air pressure, tire casing deflection, and tire footprint or gross flat plate between a standard, IF, or VF tire and their benefits:
For agricultural tires, whether using IF or VF Technology Tires, farmers can either significantly lower air pressure without compromising the carrying capacity of the tire or increase the weight carried with the same tire footprint (same gross flat plate). Both technologies allow farmers to achieve better yields or greater productivity in the field with heavier or faster machinery.
VF Tire Technology Construction uses quite different casing and rubber materials to achieve the benefits listed above by delivering the below product solutions versus Standard Tire Construction:
Original Equipment VF Tire Demand
The above +100 HP machinery-producing OEMs have adopted and will continue to add IF or VF technology tires in their product offer as the quest for increased productivity, greater yields, and faster food production continues to run in parallel with greater machinery weight and increased engine horsepower.
VF Tires with Cyclic Field Operation
In most cases, the greatest enemy of a tire is the corresponding heat generation on the tire casing that occurs as machines get heavier carry greater axle loads and operate faster. For example, the current transition in the market to larger combine harvesters evolving from class 9 to class 10 size machinery designed with greater horsepower is increasing the demand or use of tires that can offer CFO or Cyclic Field Operation capability. In essence, a CFO-engineered tire whether developed as a Standard, IF, or VF product must be able to withstand continuous dynamic loads in the field. Specifically, CFO tires are working in repetitive cycles during the harvest season with tire loads increasing and decreasing dramatically in a very quick period from light loads to heavy loads as the harvester works the field filling or emptying its on-board bin. A CFO-rated tire therefore must be capable of flexing under extreme working conditions at specific air pressures without compromising performance, traction, productivity, or soil compaction. IF or VF tire technology provides the best viable solutions to CFO or Cyclic Field Conditions as their construction materials have been engineered to provide the endurance, casing integrity, and air pressure capability to withstand both the changing load and corresponding heat generation without compromising performance.
MAXAM has developed cyclic load capability in our AGRIXTRA H family of large-volume flotation tires to meet the CFO engineering requirements as super single tire solutions for the combine-harvester market. Our current steel belted AGRIXTRA H product range has been engineered to ensure the optimal contact patch to help reduce ground pressure or soil compaction without compromising the steering or driving capability of the tire. MAXAM will be developing additional VF tires in the coming years in all our agricultural products offered with improved CFO capability to meet the global growing demand for higher load and speed capability. In addition, MAXAM will also employ our new Ecopoint rubber compound technology to rewrite the tire endurance rules and deliver value-centered products that will exceed both OEM and farmer or grower expectations.
BKT USA, Inc.
Dave Paulk: Manager Field Technical Services
IF/VF tires are becoming more commonplace in the market and are used on more equipment now than in past years. There are definite advantages in using IF/VF tires and applications where they work and perform much better than standard tires. Farms are more spread out. Farmers must get the tractors and equipment from one farm to the next by driving on the road. As equipment (tractors, sprayers, planters/seeders, cultivators, etc.) gets heavier, IF/VF tires are useful in carrying the weight of the equipment at highway speeds.
IF rated tires are made to carry up to 20% more load at the same air pressure as a standard tire. They will carry higher loads at higher air pressures than standard tires. VF tires are made to carry 40% more load at the same air pressure as a standard tire. They can also carry heavier loads at higher air pressures. When transporting equipment at highway speeds, oftentimes this higher load capacity is needed to keep the tires from failing because of heat buildup and overload. Most MFWD tractors will run at least 30 mph and most sprayers will run 40 mph. Higher air pressures are needed when transporting on the road to carry the weight and keep the tires running cooler (dissipate the heat). In some cases, IF or VF tires must be used because of the heavy weight of the equipment.
Conversely, when used in the field, IF and VF tires can be run at less air pressure to minimize soil compaction where no till and minimum till farming is concerned. They are being run at slower speeds. However, the tires must have enough air to carry the weight of the tractor and implements. Since air pressures determine ground bearing pressure (soil compaction), IF and VF tires can be run with 20% and 40% respectively less air pressure compared to a standard tire. By running less air pressures in the field, the radial tire has a wider and longer footprint to help spread the weight of the tractor or equipment out over a wider area. This also offers better traction and more fuel savings in the field.
If CTIS (Central Tire Inflation System) systems are used, tires can be inflated for road use, and deflated for field use. Low air pressures set for field use do not work on the highway. The faster a tire rolls, the less weight carrying capacity it has. Running low air pressures on the road allows tires to run hot and they don’t dissipate heat easily. This will cause the tires to eventually fail in the bead and sidewall areas.
Conversely, running lower air pressures in the field will minimize soil compaction, give better traction, and burn less fuel.
Some IF and VF tires may be labeled as IF or VF-CFO tires. CFO (Cyclic Field Operation) tires are used mainly on combines and grain carts where the loads are cyclical or changing and not constant. At slower speeds, these tires allow load bonuses for use in the field at slower field speeds.
IF-CFO tires allow a 70% load bonus at up to 5 mph cyclic, a 55% load bonus at up to 10 mph cyclic, and a 35% load bonus at up to 20 mph cyclic.
VF-CFO tires allow a 48.5% load bonus at up to 5 mph cyclic, a 35.5% load bonus at up to 10 mph cyclic, and a 13.5% load bonus at up to 20 mph cyclic.
At slower field speeds IF or VF-CFO designated tires will carry a lot of weight without having to adjust air pressures.
Yokohama Off-Highway Tires America, Inc.
Blaine Cox: National Product Manager—Agriculture, Golf and Turf
Increased Flexion (IF) and Very High Flexion (VF) Tires—and their ability to carry even higher loads under the Cyclic Field Operation (CFO) designation—are probably the most exciting technology in the tire business today, with the greatest potential to help improve productivity on the farm.
That’s because IF and VF Tires can help farmers reduce compaction force on their soils by 20 to 40%, or carry higher loads than conventional radials without increasing compaction.
IF and VF Tires are the products of amazing engineering, cutting-edge materials, and meticulous construction that allow us to construct extremely flexible, extremely tough IF and VF sidewalls and snug beads. The result is that those tires can carry extremely heavy loads at low inflation pressure without the strain and heat buildup that would occur with Conventional Radials or Bias-Ply Tires at those pressures.
With IF and VF, you can also choose which benefit you want to take advantage of: Higher Load at the Same Pressure, or the Same Load at Lower Inflation. The extra flexibility in the sidewalls and outstanding performance of the casings of IF and VF Tires create a longer, larger footprint, which spreads load to reduce soil compaction, puts more lugs on the ground for greater traction, and improves fuel efficiency. The footprint can be huge—for instance, our Alliance Agriflex+ 372 VF650/65R38 spreads its load across an area of 462 square inches.
On top of that remarkable capacity, there’s a Cyclic Field Operation Load Bonus—look for “CFO” on the sidewall like this: VF420/95R50 CFO. During harvest, loads increase and decrease as grain moves onto and off the combine or grain cart. On harvesters and grain carts, CFO changes the game: at speeds of 10 mph or less, CFO ratings allow an increase in the permitted maximum load on IF tires by as much as 55% and VF tires as much as 35.5%. At 20 mph, an IF tire can carry 30% higher load due to its CFO rating, while a VF tire in cyclic field operations can carry 13.5% more.
There are some very important restrictions to CFO use. First, the machine must operate in the field at or below the designated speed—usually 10 mph. It must also cycle through the load—it can only carry the maximum CFO load no more than 1 mile before unloading begins. Finally, CFO means cyclic field operation: on the road, the machine must be empty or operate within normal load/speed parameters.
With IF, VF and CFO capabilities, today’s best tires can help improve productivity while decreasing soil compaction. Those benefits go straight to a farm’s bottom line. Depending on soils, crops, weather and field history, soil compaction can reduce yields by 14% to 70%—and the effects can last for years.
At Yokohama Off-Highway Tires America, Inc., our Alliance Agriflex+ line of VF tires covers heavy farm machinery like Combines, Grain Carts and Tractors, as well as Floaters and Row Crop Sprayers. But we are also committed to protecting fields from all the other machinery that can cause compaction—including planters and drills, tillage equipment, manure tanks and spreaders, and other implements. We call that commitment our Alliance Whole Farm concept, and back it up with low-pressure options for nearly any wheel that touches your field.
Michelin Ag
David Graden: Operational Market Manager – Agriculture
IF/VF Tire Construction was actually invented by Michelin and first launched around 2003. The big idea behind this technology was to enable tires to carry more weight than Standard Radial Tires without really changing the size of the air chamber. This technology also gives equipment manufacturers a larger range of tires to carry heavier machines or increased hopper and tank sizes on Harvesters and Sprayers.
IF (Increased Flexion) widely hit the market first. IF Constructed Tires can carry up to 20% more load than Standard Tires at the same air pressure or they can operate at -20% less air pressure and carry the same load as a Standard Tire.
VF (Very Increased Flexion) hit the market immediately after and will carry up to 40% more load than Standard Tires at the same air pressure or they can operate at -40% less air pressure and carry the same load as a Standard Tire.
Both IF & VF Tires allow a tire to operate at its fullest capacity, meaning the footprint of an IF/VF Tire is maximized both wide and long. It allows the full width of each lug to contact the ground, in addition to more lugs on the ground, due to a longer footprint. These features, combined, will produce maximum traction and floatation for any field application. Some may think that this is just a marketing ploy, designed by Michelin, to sell more expensive tires; however, I assure you, the construction of this technology actually changes the deflection (or bulge) in the sidewall of a tire, which in turn, allows the footprint of that tire to completely flatten out on the ground.
Independent studies conducted by Harper Adams University and University of Illinois, Urbana-Champaign, both concluded using Michelin Ultraflex (IF/VF) tires, at properly recommended field air pressures, will produce up to an additional 4.31% yield. The studies were conducted over two tillage cycles in corn, soybeans and/or wheat. Additional benefits include Fuel Savings of up to 10%.
Let’s do the math on that! Consider a 1,000 acre farm at $6.79/bushel (today 9.18.23). Consider an average harvest around 200 bushel/acre, for easy math. That’s $1.358M in revenue using standard radial tires. Now, add in Michelin VF tires and it changes to 208 bushel/acre and totals about $1.4123M. Using +4% yield gain, that’s about $54,000/1,000 acres of additional revenue! Now multiply that times the number of acres you are actually harvesting and it’s a big number!
To add even more benefit, fit that machine with a Michelin owned PTG Central Tire Inflation System (CTIS) and you’ve just added complete control over your tire pressures with the push of a button. Using CTIS, offers the best of both worlds. As you enter a field, you can reduce your air pressures to field operating pressures. Remember, IF/VF tires can operate at 20%/40% lower pressures than standard tires. In many cases, a Michelin tire will operate in single digit air pressures, at field speeds and loads.
Then, when you are ready to travel down the road, at much higher speeds, you can increase your air pressures to maximize your fuel efficiency and speeds, with the push of a button.
To take it one step further, IF/VF Technology has also enabled us to add the CFO/CFO+ index to Harvester and Sprayer Tires. We are now able to publish and safely operate these tires at much lower pressures than originally offered. This technology takes into account the short amount of time a tire is under maximum pressure due to a Full Hopper or Sprayer Tank. Since this weight diminishes over time, at <10 mph, or field operating speeds, we have created an inflation pressure table which allows the user to be more precise with air pressures and truly set the lowest air pressures to carry the maximum weights, in field. As mentioned earlier, add a CTIS to this technology and you can really maximize your machine’s efficiency and productivity.
Finally, Michelin is so confident in our Ultraflex IF/VF technology, we offer a full 1-Year Total Satisfaction Guarantee on all Michelin IF/VF tires!
Yokohama TWS
Chris Neidert: AG Marketing, Training and Development Manager for Trelleborg & Mitas Tires – North America
Here we go with more acronyms in the Ag Tire World:
IF Tire Technology
IF stands for Improved Flexion, with tire capable of:
OR
How can tires with IF Technology carry the same load with less air pressure? The answer is because the sidewalls have been redesigned to carry some of the load, whereas standard radial tires use the air pressure to carry the entire load.
Benefits:
Pictured below is the inflation pressure difference between a Standard Ag Tire versus an IF Ag Tire:
Example of IF vs Standard tire sidewall and footprint:
Referring to the picture above, the IF tire on the left has lower air pressure than the standard tire on the right. This enables the tire to produce a larger longer footprint. See the difference between the red arrows? Lower air pressure enabling larger footprint provides the benefits listed above.
VF Tire Technology
VF stands for Very High Flexion. VF technology tires have a similar concept to IF tires, but the numbers associated with VF tires are larger.
VF tires have the capability to either carry the same load as a standard radial tire with 40% less inflation pressure or carry 40% more load at the same inflation pressure as a standard radial tire.
Benefits of running VF lower air pressure tires include an even larger footprint than IF, with following advantages:
Below is a comparison of the weight carrying capability between a standard tire and a tire built using VF technology.
In our example, we are using a tire size of 750/60R30.5. Both tires are inflated to 36 psi.
The VF tire can carry an additional 6,258 lbs. of weight compared to the standard tire. This represents a 40% increase in load capacity.
This advantage is particularly beneficial in the transport industry. Manure haulers, for instance, can transport a greater quantity of product and make fewer trips. This saves time and fuel, improving your bottom line.
CFO stands for Cyclical Field Operation. You can usually identify CFO tires by locating the CFO designation printed on the sidewall after the tire size.
It is a technology found in specific tires that provides an additional load bonus on top of the nominal load capacity. This load bonus is applicable to specially designed IF and VF tires when they are used in a “cyclical” condition, operating at or below 10 mph. The casing is stronger than a standard tire and its construction allows for less heat generation. In this context, “cyclical” means that the tire experiences a constantly changing load during regular machine operation. These tires are engineered and constructed to effectively manage such fluctuating loads.
The perfect and purest example of this application is a combine during harvest.
Let’s see how CFO technology will help handle the temporary overload condition that happens when harvesting. We’ll use an example of a typical combine tire size. IF800/70R38CFO 187A8 (Cyclic Field Operation)
Let us look at the load table above. When traveling at 25 mph with a tire pressure of 23 psi, the tire has a load capacity of 17,060 lbs. However, when we slow down to the harvesting speed of 9 mph, the tire’s load carrying capability increases to an impressive 26,460 lbs. This translates to a substantial 55% Load Bonus for a short distance, providing enough capacity for the combine to unload its crop. This advantage is significant compared to a standard tire, which would be overloaded in this situation. Additionally, CFO built tires are more durable and have a longer lifespan for this specific application.
CHO stands for Cyclical Harvest Operation. You can recognize CHO tires by finding the CHO designation on the tire sidewall after the tire size.
CHO technology is similar to CFO technology, but it focuses on standard tires. The casing is stronger, and its construction allows for less heat generation. With CHO technology, standard tires can handle up to 80% more load than their designated capacity. These special tires are used in harvesting situations where there are repetitive cycles, and the machine operates at or below 10 mph, covering less than 1 mile. In this context, “cyclical” refers to the continuous variation in the tire’s load during regular machine operation. These tires are designed to effectively manage these load fluctuations.
We can use the example of a grain cart during harvest.
Similar to CFO tires, let’s explore how CHO technology benefits standard tires during harvest and temporary overload conditions. For illustration, we’ll consider a tire size: 900/70R32 CHO 182A8.
Referring to the load table provided above, at a speed of 25 mph and tire pressure of 35 psi, this tire can carry a maximum load of 18,743 lbs. However, when we reduce the speed to the harvesting speed of 9 mph, and due to the CHO technology incorporated in this tire, its load capacity increases significantly to 33,737 lbs. This represents an impressive 80% load bonus for a short distance, which allows the grain cart to move to the field’s edge and unload its crop. This provides a substantial advantage over standard tires without CHO technology, which would experience an overload condition. CHO built tires are more durable in this specific application and have a longer lifespan compared to standard tires.
Wow, that was a lot of info, but that’s what we do at Ag Tire Talk. Headquarters for your technical information.
All information is provided in this blog solely to provoke thought. All deductions made from information on this site must be confirmed by Certified Ag Tire Dealer before use. Ag Tire Talk does not recommend anyone conduct tire service work with exception of Certified Ag Tire Dealer Professionals.
]]>The following is brought to you by:
Michelin Ag
David Graden: Global Account Manager – Agriculture
David Graden explains how to read load & speed index on a sidewall of a tire in this short video!
]]>
The following is brought to you by:
Michelin Ag
David Graden: Global Account Manager – Agriculture
Wonder what all the numbers in an AG Tire Size mean? Michelin’s David Graden explains all in this short interview!
]]>
AG TIRE TALK KEY TAKEAWAYS
MAXAM: “The biggest driver of combine-harvester tire choices will be dictated by the type of crop and farming practices.”
Yokohama TWS: “Small grain crops stems are weaker reducing the possibility to damage the tires- Super Singles are the predominate choice of tires vs. a Dual Setup.”
BKT: “Super singles work well on combines in dry soil and have better flotation in moist and wet soil than duals.”
ASCENSO: “Generally speaking, if the correct field CFO air pressure is maintained with VF load tables on the largest dual fitment, then we believe Straddle Duals will make the case of the best overall option.”
MICHELIN: “The easiest way for producers to compare tires in regard to soil compaction is evaluating Field Air Pressure, choosing the product with lowest inflation pressure able to carry the load at the speed they are traveling.”
PRECISION INFLATION: “Soil compaction is directly related to tire air pressure; therefore, the lower the tire pressure, the lower the soil compaction: VF CFO+ provides the lowest air pressure and most flexibility.”
YOKOHAMA: “In most situations except very wet soils, properly inflated tires can deliver equivalent traction and minimize soil compaction just as well as tracks, while eliminating the extra weight, maintenance and expense of the bogie wheel assemblies required for tracks.”
Maxam Tire International
Greg W. Gilland: Vice President Global Agriculture
It is often argued amongst farmers and growers that the most important platform in their fleet of equipment is their combine-harvester. This is the vehicle that ultimately allows them to harvest their crop to sell in the market and achieve the sustainable business profits. Harvesters, whether owned or leased, tend to be the least used piece of equipment on a farm. Harvesters are typically the longest-lasting piece of equipment in terms of total hours of use as their wear and tear only occurs during the harvest, when comparing to the service or working hours experienced by tractors or self-propelled sprayers. In some instances, depending on the care or maintenance of the equipment, it can take up to ten years to consume the original factory mounted tires. The overall key market drivers for tires or tracks employed on a harvester are listed below:
Ultimately it is the size of the farm, type of crop, and how the equipment is utilized or the inherent operational requirements that will determine the type of combine-harvester used, and the size or type of tires or tracks required. The biggest driver of combine-harvester tire choices will be dictated by the type of crop and farming practices. Below are some general guidelines that can help a farmer or grower determine what tires are most appropriate for his operation.
Note: Small Grains such as wheat are the single largest commodity crop traded worldwide.
Primary Applications Advantages for Dual Tires vs. Single Tires or Tracks
The introduction of VF tire technology with the additional 40% more load-carrying capacity per tire has helped to rewrite the load-carrying rules for either singles or duals. This technical advantage, without changing the tire sizing, is allowing OEMs to move to a new larger capacity, heavier, and increased powered combine harvesters to deliver the harvest faster. Although currently not in the AG track market as a manufacturer, MAXAM has aggressively adopted both the use of steel belts and VF technology to develop tire solutions that operate either as super single tires or as duals designed to carry heavier axle loads.
In the coming years, MAXAM will employ our new Ecopoint3 rubber compound technology to rewrite the tire endurance rules and deliver value-centered products that will exceed both OEM and farmer or grower expectations. An often-overlooked component in combine harvester applications is the growing tire loads, as stronger engine torque results in ground pressures being faced by the rear axle or steer tires that guide the vehicle. MAXAM’s steel belted AGRIXTRA H product range has been optimized to ensure that when applying the optimum air pressure, the tire tread contact patch can reduce the ground pressure or soil compaction without compromising the steering capability. Further, our VF tires are designed to deliver an optimized footprint at lower air pressures ensuring the best possible traction and flotation for any application.
Michelin Ag
David Graden: Operational Market Manager – Agriculture
This is an excellent topic! Often, I get asked this question by producers looking to minimize their down time during the harvest season, first and foremost. Second to that, they want to reduce their machine’s impact on the soil, especially in wet conditions.
Our answer for both of these questions, in addition to reducing fuel consumption, lowering maintenance, minimizing the total cost of ownership, and maximizing total efficiency is the Michelin CerexBib 2 VF CFO + in Dual Set Up.
Using this tire specifically designed for harvester application, I have seen some of the world’s largest combines harvest through standing water and saturated soils on a set of straddle dual VF 580/85R42 CerexBib 2 tires.
VF
With regard to the impact on the soil, these tires are VF (Very High Flexion) technology, which allows them to operate at 40% less air pressure than standard tires, or up to 40% more weight at the same air pressure as standard tires. This means they have a massive tractive capacity due to a larger footprint and, in turn, more lugs on the ground. As an added bonus, this large footprint significantly improves in-field fuel efficiency. As these tires work through the ground, they are able to roll over the soil instead of push through the soil, creating less resistance.
CFO
Tires are also rated for Cyclical Field Operation, or CFO, a 33% load bonus given to specially designed and constructed VF tires while that tire is being used in a “cyclical” condition and operating at or below 10 mph. “Cyclical” means that the load applied on the tire is constantly changing during the normal operation of the machine on which the tires are fitted; the tires are engineered and built to handle the fluctuating load, including when it spikes. The best example of this application is a combine with live load during harvest!
+
Tires are also rated CFO +, meaning they add another 9.5% to Cyclic Load for the Field.
In short, CFO + rating allows a producer operating at or below 10 mph to increase load under cyclical conditions by 42.5% over Standard VF Tire.
Duals vs Super Singles
Unfortunately, many folks think large single/floater tires always offer the best floatation. Where that may be true, in some cases, it doesn’t guarantee floatation and traction. In wet conditions, these wide tires can pack with mud and completely lose their tractive capacity. As these tires spin, they can create massive ruts, compact your soil and dig themselves into a hole, having a major negative impact on your yield for years to come.
Higher Air Pressure = More Soil Compaction
The easiest way for producers to compare tires in regard to soil compaction is evaluating Field Air Pressure, choosing the product with lowest inflation pressure able to carry the load at the speed they are traveling. Why?
Air pressure reductions equate to fewer Pounds per Square Inch transmitted to the soil. In other words, pressure to soil is a linear equation to Tire PSI, so as you reduce air pressure in the tire, you are reducing pressure to the soil and reducing soil compaction.
Below Study illustrates, comparing our CerexBib 2 VF CFO + tires to the competition:
In summary, our answer to optimizing combine performance in all soil conditions is using a dual tire set up with the most advanced VF CFO + tires in the marketplace, specifically designed for the harvester application, providing the lowest air pressure (lowest soil compaction) able to carry the load at the application speed.
Yokohama TWS
Chris Neidert: AG Marketing, Training and Development Manager – North America
When looking at the US combine market needs and preference, we can divide them in two large groups based on the crop they harvest, and business model and it will explain the “why” of their choices.
Winter crops – Custom Harvesters
Many Custom Harvesters will harvest wheat and small grain. They start in Texas/Oklahoma and work their way all the way up to the border with Canada as the maturity of the crop moves north. Super singles is the predominate choice of tires vs. a dual setup. The main reason would be ease of transport from one customer’s field to the next, as most of these combines are transported on trucks and the outer duals would have to be dismounted requiring additional equipment to handle them. Small grain crops stems are weaker reducing the possibility to damage the tires. Popular sizes are 800 or 900 cross-sections that can handle the weight of most small grain headers.
Midwest Farmers
They will be mainly combining corn and soybeans. In general the farmer is the owner of the combine with possibly a Custom Harvester, but in a neighborhood area. Different as with small grains, corn and soybean maturity is more concentrated in time not allowing for custom harvesters to have a long harvest run. These combines are used most often times locally and not transported on trucks. Here a dual fitment is the setup of choice. Using duals, the grower will enjoy better lateral stability in the field and when roading the combine. Many times the header stays on the machine even when roading. This dual configuration provides additional load capacity for the combine, especially when fitted with corn headers that are heavier than a soybean header.
Most popular dual combine sizes vary between 520, 580 and 620 cross-sections.
Stubble Damage Possibly Reduced
Running duals will have less stubble damage because the tires can possibly go in between the rows and help minimize stubble damage. Super singles will have to travel over the stubble and additional stubble damage can occur.
Duals vs Singles
Usually a header on a wheat harvesting combine will be lighter and the single tire set up will be OK.
Corn or soybean headers are usually heavier, sometimes up to double the weight. Running a dual set up will be able to handle that additional weight on the front of the combine.
You know we can’t have a discussion about combine tires without talking about CFO and CHO technology.
CFO & CHO vs Standard Tires
CFO stands for Cyclical Field Operation. CFO, is a technology built into certain tires that allow for a temporary (cyclic) load bonus from the nominal load capacity. This load bonus is given to specially designed and constructed VF tires while that tire is being used in a cyclic loading condition and operating at harvest speed of 10 mph. Cyclic loading means that the load applied on the tire is in constant flux during the normal operation of the machine on which the tires are fitted. The tires are engineered and built to handle the fluctuating load. During harvest, the combine increases its weight when it’s filling up the grain bin. Once full ,this load is rapidly reduced when the grain bin is unloaded reducing the load on the tires and allowing it to cool down.
CHO stands for Cyclical Harvesting Operation. CHO, is a technology built into certain conventional (non VF tires) tires that allow for a load bonus from the nominal load capacity.
This technology follows the same usage concept to a CFO technology but deals with standard size tires. CHO engineering allows a standard tire to have up to an 80% temporary load bonus from the nominal load capacity.
The perfect and purest example of these applications is a combine during harvest.
In the interest of time, let’s see how CHO technology will help handle the temporary overload condition vs a standard tire during harvesting. We’ll use an example of a typical combine tire size. 800/70R38. That tire is built in a standard size and a CHO size.
Let’s use an example of a common size combine that will be harvesting corn. The base weight of the combine is 41,778 lbs. We will add another 8,000 lbs. for the corn header. Since the combine has a 300-bushel hopper, during harvest when the hopper is full, that will add another 16,800 lbs.(300 bu x 56 lbs./bu) to the overall weight of the combine. Bringing that total to 66,578 lbs. We will use 80% of that weight is over the front axle. 66,578 x 80% = 53,262 lbs. /2 tires = 26,631 lbs. each tire will need to carry when the hopper is full.
We will refer to the below load tables. Our first tire will be our CHO tire. Using our above calculation that the tire has to carry 26,631 and we will use 6 mph CHO. As you can see that weight is between 23 psi and 29 psi. Doing some math, we will need to use 25 psi for the tire to carry the load at the 6 mph.
Here is where CHO technology really comes into play.
Using the same size tire but in a standard tire or non-CHO, you will not find that weight carrying capability anywhere in the tire’s load table. Therefore, using this tire in this particular load condition, that tire will be over-loaded during combining operations. Not acceptable.
Even if we were to try to get close, the most that standard tire could carry is 24,810 lbs. at 41 psi. The CHO tire will be able to handle that additional load and at 25 psi.
800/70R38 178D CHO
800/70R38 178D Standard
CFO & CHO Advantages:
Combine tires are an important part of your equipment. Ask your tire professional for advice.
Precision Inflation Systems
Ken Brodbeck: VP of Technology
RUBBER TRACKS
Plus:
More flotation in mud
Narrower than tires
Minus:
$ 120,000 premium over tires
Can be rough ride on pavement
Heavier than tires
More maintenance on rollers & joints
Transport causes tracks to heat up
BIG SINGLE TIRES
Plus:
Only 2 tires to maintain
Faster road speed & run cooler than tracks
Lower cost than tracks
With tire inflation system, tire psi can be
lowered in muddy soils = more flotation
Minus:
More expense to replace than duals
DUAL TIRES
Plus:
If 1 tire damaged, lower replacement cost
Big duals more stable on hillsides
Faster road speeds & cooler than tracks
Lower cost than tracks
With inflation system, tire psi can be
lowered in muddy soils = more flotation increased for transport
Minus:
4 tires to maintain rather than 2
Ascenso Tires North America
Nick Phillippi
Recommending a fitment for a specific harvester is difficult from a 30,000-foot level, whether being a manufacturer or wholesale distributor. Then when you talk about all the variables to consider- soil types, moisture condition, stubble issues, transport width, tracking down the row, local tire dealer support, customer preference, and others it gets even tougher. Not only duals vs super singles vs tracks but what about tread type, tread depth, availability of product, and even the ROI?
At Ascenso we are developing tread designs that will provide better roading wear and ride; designs specific for use in snow, on hard surfaces, and in wet conditions. Ascenso is committed to building high-quality, high-value products but also being innovative where it makes sense for the end user- using more steel belting, building full width and height tires, unique tread designs and using VF technology.
But as far as recommendations, the best person to make this decision is ultimately the producer and the local tire professional in that area. They both know the details of that farm’s use and priorities, weather history, type of crops, and other key details. Sometimes the most innovative product simply doesn’t pay you back on the cost- if you are not able to get down to the lowest recommended field air pressure with standard tires there may not be a good reason to go to VF just for the sake of air pressure.
Certainly, the 4 application basics must be met – Load capacity, speed rating, size tolerances, and wheel fitment.
2nd set of parameters – Budget, length of time of ownership left, past problems to solve, satisfaction with current setup.
Best Low Soil Compaction Set-Up
Well, you can’t be out there in wet conditions, and you have to be able to adjust air if you want compaction to be a main talking point on any vehicle, including combines.
Generally speaking, if the correct field CFO air pressure is maintained with VF load tables on the largest dual fitment, then we believe Straddle Duals will make the case of the best overall option.
Until we have onboard air in agricultural equipment, we really can’t truly give the farmer the best in field and on-road performance. Lowering and raising pressure manually is just not an option that is practical in the real world.
BKT USA, Inc.
Dave Paulk: Manager Field Technical Services
Duals
Duals work well on combines in moist to dry conditions. Duals can help carry more load and help distribute that load over a wider area to minimize soil compaction with the correct air pressures. Combines and grain carts carry cyclic loads and can take advantage of IF-CFO and VF-CFO technologies that tires offer. This allows the tires to have more weight carrying capacity at slower speeds (field speeds) without changing air pressures. In wet conditions, duals are more likely to cause ruts and collect mud between the duals. In muddy conditions, it is necessary to keep the mud cleaned out between duals to decrease the possibly of stalks and rocks damaging the sidewalls of the tires. If the field is too wet, and ruts are deep, it takes some time to repair the soil from the compaction caused.
Super Singles
Super singles work well on combines in dry soil and have better flotation in moist and wet soil than duals. In moderately dry soil, super singles have a much wider footprint to distribute the weight of the machine and load and minimize soil compaction. Some super singles are IF or VF-CFO tires and can carry larger loads at slower speeds. Super singles do not cause ruts as bad or as deep as duals in wet and muddy soil. Depending on the type of soil, super singles may not clean out as well because of the width of the tires. If they don’t clean out as well as they should, similar to duals, they can become slick and lose traction. This could cause deeper rutting, damage to the soil from spinning, and possibly damage to the tire.
Tracks
Combines may have tracks, or a mixture of tracks on the front and tires on the rear for maneuverability and steering. In wet and muddy conditions, tracks seem to work well because of the width and length to distribute the weight of the machine and load over a much larger area. They provide good traction and good flotation. The track and undercarriage use dirt as a lubricant in the field, but needs to be checked occasionally for rocks, sticks, and stalks to minimize the possibility of damage by rocks and stalks. They can cause ruts in wet and muddy dirt, but generally not as extreme as duals. Since they are wider and longer, they float over the dirt better.
In moist and dry dirt, all three setups work well. With the right tires and air pressures, all three can be used to minimize soil compaction and provide good traction. When compaction can be neutralized, crop yields improve.
Roading
Pneumatic tires seem to wear better and smoother on the highway than tracks when moving between fields, especially with long distances. When roading distances are required, the crown of the road can cause some right-side tire wear. Because of the width of combines, they run at the edge of the road. This generally shows up in the smaller tires first because they turn more. The usable hours on tracks are shortened with a lot “roading” activity. Depending on the track setup and brand of undercarriage, tracks speeds can be a little slower while roading than a combine using tires.
Maintenance
On tractors with pneumatic tires, there is a tire, a wheel, and a hub. Although tires and wheels can be expensive when needing to be replaced, there isn’t much maintenance required. As long as the wheels are kept clean and the tires run at correct air pressure, they are usually problem free.
Tracks have many more moving parts. They have drive wheels on positive undercarriages, or guide wheels and idlers on friction undercarriages. Occasionally, the idlers need to be replaced. But more often, the mid-rollers wear out the fastest because they carry most of the weight. Tracks and the labor to install them are expensive. They must be aligned when tracks are replaced to prevent damage from the drive or guide lugs. They must be kept clean from rocks, sticks, and other debris getting into the drive lugs and cutting the inside of the belt. Tracks are somewhat more expensive to take care of but can provide good flotation in wet dirt and good traction in dry soil.
Condition Dependent
There are some differences between these three setups, but all can be used in the right conditions. In a perfect world, if no till or minimum till farming is used, it’s best to stay off the field in muddy conditions to minimize the possibility of compacting the soil. It takes a while to repair it once this is done. Unfortunately, it isn’t always possible to do this when a crop must be taken out. A farmer can use the setup to help them the most in these conditions.
Yokohama Off-Highway Tires America, Inc.
Blaine Cox: National Product Manager—Agriculture, Golf and Turf
There are a number of variables to consider when deciding between duals and large singles on combines, ranging from the size and capacity of the machine to the soil type, moisture levels, and even the width of local roads. In most situations except very wet soils, properly inflated tires can deliver equivalent traction and minimize soil compaction just as well as tracks, while eliminating the extra weight, maintenance and expense of the bogie wheel assemblies required for tracks.
Tires are also more fuel efficient than tracks, and are significantly better on the road—they ride smoother and last longer when roading compared to tracks.
Dual configurations can spread the load over a larger surface, which is obviously effective for reducing soil compaction force. However, if you are using the combine in gumbo, sticky mud or muck, the space between the duals can fill up with mud, reducing overall performance. Also, for many operators, the result can be a combine too wide for roading or even storage in some sheds, and, of course, more tires means more cost. As an alternative to duals, our Alliance Agriflex 372 IF (increased flexion) tire comes in a 1250/50R32 size that provides more than four feet of width on each tire for massive surface area in a single-tire configuration.
VF (very high flotation) tire technology has also dramatically changed farmers’ options when it comes to tire performance in combines. VF tires like the Alliance Agriflex+ series can operate at 40% less inflation pressure under the same load as conventional radials. In addition, farmers can select among a range of tread patterns to best suit their soils and conditions, providing greater flexibility than most track options.
High-capacity tires—in dual or single configurations—can be a high-performance, cost-efficient alternative to tracks. Since inflation pressure is such an important part of performance, it’s worth considering also investing in a central tire inflation system (CTIS), which allows the operator to adjust inflation pressure on the go. That ensures a low, compaction-minimizing inflation pressure on the field and a quick switch to a higher pressure for better roading. Optimizing inflation pressure ensures optimal performance, and can add significantly to tire life, making CTIS an investment that pays itself off very quickly.
Just as important as the tires is how you use the combine. If compaction is a concern, consider not filling up the grain tank—instead, offload grain sooner, while minimizing cart or semi traffic “shortcuts” across the field. Make sure your grain cart tires are also high-flotation, and that they are inflated properly to minimize compaction.
Finally, while combines, grain carts, and tractors get the most attention when it comes to soil compaction, it’s important to remember that every machine that touches the field can create or worsen soil compaction. At Yokohama Off-Highway Tires, we created the Whole Farm concept, a commitment to develop low-compaction tires for nearly any piece of equipment used in the field. The Whole Farm concept draws on our VF, IF and flotation tire technology to minimize soil compaction all year long.
Also, our Alliance 372 VF and IF rated harvester tires come with a CFO (cyclic field operations) rating. That allows for high cyclic loads while harvesting, which adds up to an additional 55% load at 10 mph or less and an additional 30% if you are running at 20 mph or less. That is an enormous amount of additional load capacity on a tire that is protecting the soil from excess compaction force.
All information is provided in this blog solely to provoke thought. All deductions made from information on this site must be confirmed by Certified Ag Tire Dealer before use. Ag Tire Talk does not recommend anyone conduct tire service work with exception of Certified Ag Tire Dealer Professionals.
]]>How to use a Load Inflation Chart setting your tires to the exact air pressure to enable you to maximize yield.
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