Tire Selection

• Selection of size and Ply Rating on each axle shall be based on the highest individual wheel load (as determined below) when vehicle is weighed statically. Maximum load per tire shall not be greater than specified in applicable tables.
• For sustained high torque service – Drive wheel tires on Agricultural tractors operating in the field must be selected to withstand the maximum pull of the tractor under normal operating service.
• Maximum speed for most Agricultural tires is 25 mph.
• Radial R-1 and R-1W drive tires can operate at 30 mph and “FI” tires are highway speed capable.

Maximum Load – Maximum loads on individual tires are determined by considering the maximum axle load on each half of the axle and dividing by the number of tires on that half. The maximum load in field service or transport is to include:

• Net Weight – Defined as the actual weight of the vehicle with standard equipment, including the maximum capacity of engine fuel, oil, coolant, and operator (170#).
• Accessory Weight – Combined weight of those installed production items not previously considered in “Net Weight” (such as air-conditioner, etc.) Optional Equipment Weight – Difference in net weight between the optional item and standard item replaced (such as engine, brakes, tires, etc.). This is to include the net weight of additional items offered by the manufacturer which are not replacements for standard items (such as cabs, sideboards, etc.).
• Tire Ballast – If used, must be included in determination of maximum load.
• Field Modifications – Net weight change due to vehicle alterations made by those other than the original manufacturer (such as modifications for additional capacity, reinforcements, etc.).
• Bin and Tank Loads – Includes total weight when full.
• Implements – Includes that portion of the weight of any implement carried by the axle.
• Cyclic Loading on Agricultural Harvesting Equipment – Gradual increase of payload to maximum allowable load (see appropriate tables and notes) with unloading before off-field transport.

Hillside Combine
Combine intended for service on slopes above 11 degrees (20% Grade).

Operating Conditions
Refer to footnotes in appropriate tables.

Minimum Dual Spacing
Minimum dual tire centerline to centerline measurement.

For Tractor Drive Wheel Tires

Bias Tires
Design Section Width x 1.10 + 1.50 inches.

Radial Tires
Design Section Width x 1.20 + 2.00 inches.

L (In Size Designation)
Low section height agricultural tires.

SL
Service limited to agricultural usage.

FI
Tires for use only on farm implements in agricultural service with intermittent highway use.

NHS
Not for highway service.