F-1 is free rolling single rib steer tire, best suited for wet mucky soils, typically complementing rear R-2.
F-2 is free rolling 3-Rib steer, general dry land farming tire, typically complementing rear R-1.
F-2M is free rolling 4-Rib steer, general dry land farming tire, typically complementing rear R-1.
I-1 is free rolling multi-rib tire, used on variety of towed implements.
F-I is free rolling multi-rib tire (same tread pattern as I-1); however, it is DOT approved for specified highway service speeds.
R-1 is bar tread drive tire used for general dry land farming.
R-1W is bar tread drive tire (same pattern as R-1), best suited for wet sticky soils, with approx. 20% deeper tread than R-1.
R-2 is bar tread drive tire used for wet mucky soils (rice & cane), with approx. double tread than standard R-1.
R-3 is button tread drive or free rolling tire designed to minimize soil disturbance, approximately half the tread of standard R-1.

SIZE EXPLANATION (How to Read AG Tire Size)

Standard Size
18.4 = Section Width (inches)
R = Radial
42 = Rim Diameter (inches)
*18.4-42 (Dash between Section Width and Rim Diameter) indicates Bias.

Metric Size
480 = Section Width in Millimeters
80 = Aspect Ratio (% of sidewall height to section width)
42 = Rim Diameter (inches)
*Most new tire offerings use Metric Sizing.

Convert Metric Size to Standard Size
Divide the metric number (millimeters) by 25.4 to get inches.
480 Section Width / 25.4 = 18.9 inch section width.

Convert Standard Size to Metric Size
Multiply standard (inches) x 25.4 to get millimeters.
18.4 Section Width x 25.4= 467 millimeter section width.


Bias ply cords extend DIAGONALLY from bead to bead.
Radial cords extend from at RIGHT ANGLES from bead to bead across tread.

Radial is superior to Bias as enables larger footprint, better traction, and reduced fuel.


Ply Rating
Designates maximum load carrying capacity of a specific size tire at maximum air pressure and speed. Predominately reserved for Bias ply.

Star Rating
Designation related to a standard maximum air pressure. *=18 PSI, **=24 PSI, ***= 30 PSI, with Maximum Load varying by size. Star rating system is falling out of favor, with Ag Tire manufacturers preferring Load Index Chart.

Load Index
Designates maximum load carrying capacity of a tire at maximum air pressure and speed, in accordance with Load Index Chart that can be viewed by clicking below link:


Designates maximum speed of tire in accordance with Alphabetical Speed Rating Chart (A to Z).

Ag Tire Speed Ratings

A8 = 25 mph
B = 31 mph
C = 37 mph
D = 40 mph
E = 43 mph
F = 50 mph

480/80R42 with 151B Load Speed Index:
151B = 7600 lbs @ 23 PSI Max Air Pressure at 31 MPH.


Tire identification number stamped on sidewall of Ag tire indicating manufacturing plant, size, date of manufacture, and certifies compliance with U.S. Department of Transportation highway service standards where applicable.

DOT stamp indicates tire is approved for highway service by U.S. Department of Transportation
CF is plant code: Titan Des Moines Iowa
HR is size: 480/80R42 (Optional for Manufacturer)
FOWR is brand or other type: Hi Traction Lug (Optional for Manufacturer)
4202 is date of manufacture: 42nd week of 2002

Manufacture Date note:  Starting in 2000 date coding changed from 3 to 4 digits as shown above.  3 digit 202 means tire was built 1999 or earlier, 20th week of 1992, 1982, or 1972, but not 2002.

Plant Code note: On April 2015 NHTSA (National Highway Traffic Safety Administration) ran out of 2 digit plant codes, changing to 3 digit codes. Existing 2 digit codes will be phased out no later than 2025.

Ag Tire Plant Code Key
AG, 2A6 JK Tornel Tacuba Mexico
A9, 1A9 Titan Tire Bryan Ohio
B4, 1B4 Taurus (Michelin) Budapest, Hungary
B5, 1B5 Stomil (Michelin) Olsztyn Poland
CD, 1CD Alliance Hadera, Israel
CF, 1CF Titan Tire Des Moines Iowa
C4, 1C4 Carlstar Group (Carlisle) Clinton, TN
FO, 1FO Titan Tire, Natchez, Mississippi
FY, 1FY Balkrishna Industries Ltd (BKT) Kutch, Gujarath, India
LH, ILH Speedways Rubber Company, Jalandhar India
LW, 1LW Trelleborg
P4, 1P4 Carlstar Group (Carlisle) Jackson, Tennessee
PK, 1PK Titan Tire, Freeport, IL
UD, 1UD Mitas Tires North America Inc. Charles City, Iowa
VE, 1VD Bridgestone Corporation Des Moines Iowa
WN, 1WN Trelleborg Xingtai, Hebei, China.
3U, 13U Specialty Tire Unicoi Tennessee
3V, 13V Balkrishna Industries (BKT) Waluj, India
4F, 14F JK Tornel Tultitian Mexico
5F, 15F JK Tornel S.A. de C.V.
4L, 14L Carlstar Group (Carlisle) Bu Ji Town China
6I, 261 Michelin / Taurus Nyiregyhaza, Hungary
6J, 16J CGS / Mitas Zlin, Czech Republic
6N, 16N Mewat Tire & Rubber Ltd. Rajasthan, India
8S, 285 Petlas Tire Industry Kireshir, Turkey
9N, 19N Balkrishna Industries Ltd. (BKT)
26, 126 Malhotra Rubber Ltd. Nodia, India
35, 135 Trelleborg Lanka (Pvt.) Ltd. Sapugaskanda, Sri Lanka
54, 154 CGS / Mitas A.S. Prague, Czech Republic
*Above list is abbreviated for reference only.  If you have question on plant identification code not listed, please ask on Ag Tire Talk blog.  One plant may have multiple codes assigned.






Alliance Tire Group (ATG)



Specialty Tires of America (STA)


*Bold indicates parent company with owned brands underneath.

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.