Tire Casing Construction: Poly vs Nylon vs Steel

by | Aug 30, 2021 | Featured, Tire Technology | 0 comments

AG TIRE TALK KEY TAKEAWAYS

MICHELIN:  When choosing best tire construction, it all comes down to application, as Nylon/Polyester/Steel Belt/All Steel Casings all have different features and benefits.

CONTINENTAL: Nylon provides mid-range stability and medium shrinking, but is excellent in absorbing energy.  Polyester offers better dimensional stability than Nylon and low shrinking, but only an average level of energy absorption.

GRI:  Tire manufacturers use steel belts with a nylon polymer casing for tread stabilization.

ALLIANCE:  The steel belts help us ensure a flatter contact patch for better traction and more even wear, which is enhanced by the flexibility of the synthetic plies…steel belts also provide puncture protection.

BKT:  All steel casings have a steel belt instead of a fabric belt running from bead to bead in a radial design….allowing for higher inflation pressures, more load carrying capacity, lower rolling resistance, higher speeds, and casing durability.

MAXAM: …we are seeing an evolution of ag tires toward nylon radial casing with steel belts or steel casing with steel belts.

 

Maxam Tire International
Greg W. Gilland:  Business Development & Ag Segment Manager

The global tire market today is broken into segments determined by equipment, application, and use. As a rule, the largest global equipment segments are the passenger vehicle and commercial trucks, accounting for well over 85% of all tires sold annually. In these segments, radial tires make up 99% of carcass construction. In comparison, the specialty-equipment market that includes construction, mining, agriculture, aviation, and motorcycle/bicycles includes both radial and bias ply carcass constructed tires. The primary difference between radial tires and bias ply tires is in the tire carcass and the material construction of the tires. Below are examples detailing the differences between the two types of tire construction:

The key difference between the two types of construction is how the radial tire uses the single radial casing as a spring mechanism to push the working belts onto the working surface. This ensures a uniform contact patch or contact area for the tire tread to deliver both the necessary traction and friction to carry the required load in any direction under power. In the case of bias ply constructed tires, which reflect tire design concepts from over 100 years ago, the carcass is made up of multiple plies of material that function as a single unit like a balloon to push the tread onto the surface area. Under a working load both tires work very differently as to how the tread area or tire footprint will function to deliver the needed traction or friction to move a vehicle forward:

The improved footprint and traction delivered by radial tires has accelerated the transformation of the specialty segment towards fully adopting the radial tires as the primary type of tire construction on both new and older equipment. The market evolution to radial tires from bias ply tires continues to march forward as technology demands improved tire grip, load carrying capability, and enhanced traction. In most cases, bias ply carcass constructed tires are built with either nylon or polyester threads stacked as needed to achieve a certain strength rating or ply rating. Although MAXAM products a limited range of bias constructed implement tires, our primary focus is high-performance radial casing constructed tires designed to deliver the optimal traction, grip, and performance that modern equipment required to do the job efficiently. Every tire is a compromise between load-carrying capacity, working speed, and the gross flat plate or tire footprint necessary to do its job. By using different types of materials in the tire casing we can enhance or provide improved performance with the objective to deliver the optimal performance required ensuring improved traction, reduce soil compaction, and service life.  MAXAM radial ag tires have the following material construction possibilities:

As agricultural machinery continues to grow in weight and engine horsepower, we are seeing an evolution of tires toward nylon radial casing with steel belts or steel casing with steel belts. MAXAM’s radial implement I3 FLOTXTRA line of tires are steel casing with steel working belts designed to meet the high speed and high load requirements of heavy towed implements or tanker-type trucks. In addition, we are seeing the migration of compact construction equipment into the ag world to carry out or support all the jobs that a farming operation requires. Over the last 25 years, we have seen skid steers and backhoes become integral parts of any farm or grower’s operation. New additions to the agricultural and rental equipment world coming to North America having been successfully employed in the European market are telehandlers, wheeled excavators, and compact wheel loaders. European agriculture is made up of smaller farms with tighter road restrictions that rely heavily on radial tires due to the high load and high transport speeds required.

As a result, MAXAM has developed new radial tire solutions optimizing both the tread and casing construction to deliver the value and performance that customers expect from Maxam Tires:

Backed by a world-class warranty program, our radial tires are manufactured to maximize performance, reduce compaction, improve traction, and increase your productivity!

 

Continental Agriculture North America
Dana Berger, Ag Business Development Manager at Continental Commercial Specialty Tires

When it comes to tires, the carcass is the drop of water that causes a ripple effect, in a pond. Without a strong, stable beginning, what could have been a masterpiece, will fall apart in an instant. A tires carcass requires real attention to detail, as it is responsible for the damping and flexion of the tire. It must be constructed with quality materials and an imaginative approach, to be able to address various applications.

Commonly used textile materials; nylon, polyester and rayon, allow for this flexibility and imagination. Each has its own positive, or negative attributes. Nylon provides mid-range stability and medium shrinking but, is excellent in absorbing energy.  Polyester offers better dimensional stability than Nylon and low shrinking but, only an average level of energy absorption. Rayon is different still. Like Polyester, it allows good stability, but will degrade when wet; which, shortens its long-term endurance. Continental selected nylon and enhanced it with N.Flex technology, that incorporated high elongation capabilities and allowed it to compete with the stability level of polyester. The strength benefits increased when adding twists to the textile cord, providing impact resistance and a robust construction for our tires.

Our CompactMaster line, incorporates two steel belt layers providing lateral stiffness and support for tilting stability. Steel, rayon and polyester, are the typical belt types. Of the three, steel is the strongest, has the best cut resistance and is very stiff. With the right steel cord, we can reduce the number of layers (or plies) required to create a strong, puncture resistant tread area. Polyester is a fine choice for a tractor tire but, for tires with high inflation pressure requirements, like the CompactMaster, the strength of polyester may be subpar. Although the steel is stiffer, it requires fewer plies to construct a stable tire; therefore, it behaves softer radially and laterally. Both effects are supported by the tailored design of the steel cord. Each cord is a bundle of several thin wires, twisted around each other. The unique twisting of the steel cords, used in Continental’s CompactMaster, allows the tire to maintain it’s elasticity, while still providing key benefits that other steel belted tires promote. Because steel belts are so sturdy, they form a more even footprint and large contact patch for better traction and reduced slip.

William Cowper, an English Poet, wrote, “Variety’s the very spice of life, that gives it all its flavor”, and that is just as prevalent with the types of tire carcasses. The challenge: matching the spice to its best application. Just like pairing wine to a charcuterie board, or particular protein, a tire manufacturer must pair the carcass construction style to optimize its performance. This becomes relevant with Skid Steers, Telehandlers and Compact Loaders.

Skid Steers are the universal light construction machines. The versatility they have, expands from light applications on smooth, or loose surfaces, to extreme conditions and rocky terrains. It is difficult to accommodate such an array of demands; so, two tire constructions have emerged, as the top runners in the market. The more cost efficient, bias or cross-ply tires. This style is robust, provides good sidewall protection and is usually easily sourced. Our General Tire brand offers a standard-duty, heavy-duty and extra heavy-duty option. These tires are developed with a cut/chunk-oriented tread compound and are resistant to abrasion. In heavy applications with high risk for flats, a maintenance free option is a fully solid tire, or Super Elastic. Next year, Continental will launch the CompactMasterSolid a skid steer focused tire line, to meet the needs of these customers.

Telehandlers have similar demands on tires, but due to the booms, stability is a necessity. Telehandler tires must be durable, have excellent stationary stability, good traction for loose ground and be puncture resistant/maintenance free. Depending on the application, solid or pneumatic tires can be used. Currently, Continental offers a solid version – the TeleMaster. This is a robust, ‘easy keeper’ and provides excellent stationary stability. Pneumatic tires come in two versions, bias and radial. Bias, as mentioned with skid steers, can be more cost friendly, unless foam filled. They have stiffer sidewalls than their radial counterpart and the ply angles, reduce the movement in the tires tread area. Radial tires are not as common as the bias version, but with new technologies on the horizon, we may see an uptake in some applications. Our CompactMaster AG/EM and MPT70E, can be sourced for some small to mid-range telehandlers.

Compact Loaders (including backhoes) operate in diverse construction operations from rugged, rocky terrain, up to smoother sand/soil surfaces. Demand on the dexterity and distances of these machines, varies – which makes two different carcass concepts, suitable. The value option is again, the bias tire construction. This tire is useful for small sites, where the operator is driving shorter distances and load cycles. We offer our General Tire V-ply tires, for applications such as this. Radial tires with steel belts, like that in our CompactMaster tires, protects the tread against foreign object penetration and radial tires will run cooler, with less heat propagation on long runs. Radial construction is also, more flexible and tolerant of agile movements from the operator.

 

GRI Tires
MAHAJANSHETTI M.H., DIRECTOR- TECHNICAL

An important milestone in human history was the beginning of agriculture. Its primary function is to produce food to meet demand. Agriculture is constantly updated with ever-evolving technology. All types of vehicles, tires and machinery manufactured with modern technology play a large part in increasing agriculture production. The tire industry is developing rapidly to meet agriculture needs.  A quality tire at an affordable price is a huge advantage. Identifying the most effective tire for the application is important and advantageous. Some high-tech modern tires are expensive yet no more productive to use outside of the proper application. Nylon and polyester body plies and belts are traditional. Recently developed high quality nylon variants, such as Nylon 66, are used to manufacture and improve agricultural and industrial tires.  Some of the benefits of the nylon variants are as follows:

  • Improved fabric integrity at elevated temperatures as heat destroys tires
  • Improved mechanical strength (think NFL lineman)
  • Improved toughness, stiffness and hardness (like an NFL linebacker)
  • Improved fatigue resistance (being fresher at the end of the day)
  • Improved impact resistance (akin to armor)
  • Improved wear resistance
  • Lightweight (takes less effort – fuel and wear & tear)
  • Improved fuel and oil resistance (increased durability)

Body plies and belts determine the load carrying capacity of tire (i.e. ply rating or load index) of bias or radial tires. The body plies and belts can be nylon, polyester, a mix of nylon and polyester, steel belted with nylon/polyester body ply, or all steel or aramid. Some of polymer fibers like aramid have enough strength for bulletproofing. As a premium tire manufacturer, GRI makes tires with different body plies and belts depending on the application. To meet the requirements of customers, GRI plans to introduce steel belted radial and all steel tires within 9 to 12 months.

Polyester/nylon tires provide the best performance for select applications. Below are a few considerations producers should evaluate when choosing tires.

  • Traction (increased traction saves fuel & time)
  • Load Carrying capacity (saves fuel & time)
  • Soil compaction (reduced soil compaction increases yield/profits)
  • Durability (reduced down time increases production and reduces expenses)
  • Driver comfort (Fresh operators increase production)
  • Value for the money (the lowest acquisition cost often has the highest operating cost)

Selecting the right tire for the application impacts the following:

  • Fuel efficiency
  • Crop yield
  • Vehicle efficiency (wear and tear)
  • Soil or crop root damage (yield)
  • High carbon sequestration (Global warming)
  • High vehicle maintenance and downtime (production)
  • Increased operator fatigue (production)
  • Tire fouling vehicle body (maintenance and/or production)
  • Vibration (maintenance)

Identifying the right tire for the application is important for optimal productivity.  Tire manufacturers use steel belts with a nylon polymer casing for tread stabilization and other tread related matters. This construction method is also used to meet the requirements for hard surface tire applications of construction vehicles such as skid steers, telehandlers, and compact loaders.  All steel tires are stiffer than steel belted tires as the steel is included in the side wall. All steel tires improve puncture resistance, dimensional stability (keep their shape) and are more durable in applications where you tear them up before you wear them out, such as, construction, ports, warehouse, and factories.

GRI makes great strides in the tire industry across the globe ensuring our journey towards perfection… as Vince Lombardi once said “we will chase perfection, and we will chase it relentlessly, knowing all the while we can never attain it. But along the way, we shall catch excellence”.  Our journey of excellence continues…

 

BKT USA, Inc.
Dave Paulk: Manager Field Technical Services

In the early days of tire manufacturing, cotton was the fabric most used to make the body plies of a tire carcass.  An 8-ply tire had 8 cotton plies, a 10-ply tire had 10 cotton plies, and so on. With the invention of synthetic materials like nylon, polyester, and rayon that are stronger and more resilient than cotton, tire casings require less material (less body plies) to have the same strength as cotton plies. The synthetics used today have improved strength and wear benefits over cotton and have taken its place in tire manufacturing.

Although there are unique differences between nylon and polyester, both are important in ag tire manufacturing. It isn’t so much a matter of preference, but where do they work best in the manufacturing process and in the quality of tires produced.

Nylon was the world’s first man made fabric invented in 1935. Although it was used extensively in WW II by the military, it was not available to the public until after the war. Nylon was produced as an alternative to silk and was first used as bristles for toothbrushes. Most nylon is made from unavoidable oil refinery by-products. It has low moisture absorbency, is resistant to damage from oil and many chemicals, is abrasion resistant, and has greater elasticity. Nylon is the second most used fabric behind cotton.

Most bias belted agricultural tires are made with nylon. Nylon is a stronger fabric and bonds with rubber much better than polyester. Nylon allows for greater strength with less body plies. Nylon has a greater degree of elasticity which allows bias tires to grow some when aired up, but once nylon is stretched with air pressure, it doesn’t shrink back.  Some bias belted rear farm tires built by BKT are the TR135, TR 137 (combine sizes), TR 117 (irrigation sizes), and skid steer tires (Skid power line, Mud Power, Giant Trax, Jumbo Trax). Bias belted skid steer tires and telehandler tires work well because of the stiff sidewalls and low lateral movement.

Polyester made its debut in the early 1940’s and didn’t become popular until the early 1950’s. Polyester is non-biodegradable but can be recycled. Polyester disseminates heat faster than nylon. It also has low moisture absorbency, is strong and lightweight, and has less elasticity than nylon. This helps the tire maintain it’s shape.

Polyester is used mainly in radial tires for rigidity and stability because of the low rate of shrinkage. This allows for consistent sizing between brands. It can also be used in high-speed bias tires for casing integrity as polyester does not grow in service like nylon. Polyester does not flat spot when cold like nylon does. Many of BKT’s radials such as the Agrimax series, Spargo, Teris, and Sirio incorporate polyester in their construction.

There are also differences in all-steel casing and steel-belted tires.  Both have their advantages in different applications.

All steel casings have a steel belt instead of a fabric belt running from bead to bead in a radial design. In all steel casings, there is generally only one steel belt in the sidewall. Since steel doesn’t shrink or stretch, it allows for a consistent sized casing. The steel belt helps the tire keep a flatter footprint and gives the tire carcass strength.  They allow for higher inflation pressures, more load carrying capacity, lower rolling resistance, higher speeds, and casing durability. All steel casings have a higher ply turnup around the bead and are easier to repair sidewall cuts and punctures.  Some BKT agricultural tires that have all steel casings are the Multimax MP569 (new tire) and MP540, the Ridemax FL699, the FL633 Performa, the SR713 (radial implement tire) and Skid Max Skidder (260/70R16.5).

Steel belted tires are designed with fabric, like nylon or polyester, carcasses with a steel belt (or multiple steel belts) overlaid under the tread area. This provides a flatter footprint by making the casing rigid and has better penetration resistance. It can also reduce rolling resistance. The benefit of the flatter footprint gives the tire better traction, even wear, better handling, and a longer tire life. Some BKT agricultural steel belted tires include the FL630 Super, Multimax MP515 and MP513, Ridemax FL693M and FL 690, FS216 (Forestry tire), AW711 (in some sizes), and the Rib 713 (radial implement tire).

While skid steers, telehandlers, and compact loaders equipment have always been popular in construction and industrial applications, skid steers and telehandlers have become more widely used in agriculture, especially in dairies and feed lots.

Most skid steer tires are made with nylon casings because of the strength of the casing and its ability to take punishment under severe conditions.  The tread is compounded for different applications depending on what the tire is designed for.  Some are made with chip/chunk resistant compound, and some with special industrial compounds to provide longer life on hard surfaces.

BKT makes various designs for telehandlers and skid steers and loaders. The BKT Lift Star Plus is a popular design that works well for telehandlers. BKT builds the MP567, MP522, and RT747 for telehandlers and skid loaders.  Whatever the application, BKT has a tire built with optimum casing/carcass construction to fit.

 

Michelin Ag
David Graden: Operational Market Manager – Agriculture

When choosing best tire construction, it all comes down to application, as Nylon/Polyester/Steel Belt/All Steel Casings all have different features and benefits.

When determining the right tire for your application, consider what you will be doing with your machine, then write a checklist of what you want to get out of the tire.  Here are some examples:

  1. Will you be doing Severe Duty Skid Steer Work in Concrete Application with possible curb impact?
    1. Our All Steel Casing BibSteel is perfect for application.
  2. Do you need additional puncture resistance for Telehandler used for hay application in Rough Service Environment:
    1. Choose our XMCL Steel Belt to reduce punctures.
  3. Do you need a tire for your Trailing Implements that can handle Field Stones & Stubble?
    1. Our BFG Implement Control tire is a Steel Belted Radial with cut and chip resistant compounds.

If we take a look at Radial Ag R-1/R-1W Tractor Tires, there isn’t much need for steel belts, unless your machine and application demand that additional carrying capacity. As a general rule polyester is known for better ride characteristics, whereas nylon is known for increased durability.  The need for one of these over the other can also be determined by how much or little flexibility is needed for this tire to perform at it’s potential. At Michelin we build most of our VF Ultraflex tires with nylon, as it allows us to create a more flexible carcass while improving durability over our standard tires.

Whatever your needs, Michelin has the answer- in fact, each one of our field sales reps carries a set of scales and is equipped with the knowledge to help you dial in on your exact needs for the specific application.

 

Yokohama Off-Highway Tires America
Ryan Lopes
National Product Manager—Material Handling & Solid Tires

Though our selection of carcass ply material is often proprietary information (like compound formulations), the choice between polyester and nylon in light construction tire casings is typically a matter of balancing strength, adhesion, weight and cost with the demands of the application.

Construction tires are most often required to carry heavier loads, so strength is always important. The movement of different types of equipment places unique requirements on tires. For instance, a skid steer skids its tires to turn, which makes heat dissipation critical and wear properties of the compound essential. At the same time, a telehandler requires a tire with a strong, reinforced sidewall to minimize tire deflection to prevent the equipment from toppling over when its boom is extended. In both of those cases, we would engineer a carcass with a suitable number of plies and an appropriate material to optimize performance and maximize tire life.

Of course, all-steel construction offers the combination of durability, strong adhesion, and excellent heat dissipation, which is why you’ll see it in premium ag and construction tires designed for high-strength, high-speed applications.

Several of our most popular multiuse and light construction tires, such as the Alliance 550 and Alliance 551, for example, feature synthetic body plies overlaid with steel radial belts. The steel belts help us ensure a flatter contact patch for better traction and more even wear, which is enhanced by the flexibility of the synthetic plies. Of course, the steel belts also provide puncture protection.

Another aspect of many of our tire designs lies in innovative uses of cap plies and belt edge strips, which allow us to tap into various materials to provide added functionality and enhance tire life.

Like compounds, ply materials can be very creatively managed and combined in a tire design to optimize function.

 

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.