In the current Ag market, producers are trying to get the most efficiency out of their tractors to control costs. The efficiencies operators are looking to include are maximizing traction, covering more acres in less time and improving crop health by limiting soil compaction. The tires used on tractors and the inflation pressure required can be the biggest contributor to improving traction and controlling soil compaction. When operators start looking at tire options, there are multiple questions asked by the tire dealer:
- Tire construction: Radial or Bias.
- Tread Depth: R-1, R-1W, R-2
- Standard radials, IF radials, or VF radials.
When faced with these questions all at one time, operators may feel like a deer in the headlights. To avoid that feeling and to prevent you from saying, “just give me something that works,” here are a few explanations to the questions so you can be confident making a tire purchase.
Radial or Bias Tires
When purchasing tires for a MFWD tractor used for primary tillage or planting, radial tires are more efficient than the same sized bias tire. When properly inflated, radial tires develop a longer footprint compared to the bias tire and carry the same axle load at less inflation pressure. The longer footprint allows for more tread bars to make contact with the soil, and it develops more traction. More traction results in less slippage and that allows for more work to be completed in the short planting and harvesting window. Research conducted by tire companies, equipment manufactures and land grant universities showed that radial tires developed 6% to 14% more traction versus the same sized bias tire. This increase in traction resulted in more work being done per hour, less fuel being used per day and fewer hours put on a tractor each year.
The longer footprint of the radial tire also results in a longer wear life compared to the bias tire. This longer life is directly related to the fact that there are more tread bars making contact with the ground which reduces contact pressures. Reduced contact pressure means the tread bar will not wear out as fast. The improved wear life is one of the major reasons radial tires are used on cars, light trucks, and large trucks.
Radial tires are also designed to carry the same load as bias tires with less inflation pressure. The ability to use less inflation pressure results in less soil compaction improving crop health. When properly inflated, radial tires have the signature sidewall bulge or look flat compared to the bias tire. This bulge, or sidewall deflection, is what allows the tread to have the longer footprint. The deflection also allows for a softer ride, which could help reduce operator fatigue after a long day driving on rough ground.
Yes, radial tires do cost more because of the materials used and how they are constructed. This cost difference is offset by the increase in traction, reduction in fuel cost, longer tire life, less soil compaction and a more comfortable ride.
Tread Depths: R-1, R-1W, R-2
The agricultural tire industry classifies the tread depth of traction tires using the nomenclature R-1, R-1W, and R-2. This marking helps tire manufactures standardize the tread depth of a tire, so operators can properly compare tires. The R-1 tread depth is the base tread depth for that size. Tires marked R-1W have a tread depth that is 20 to 30% deeper than the same sized R-1 tire. The tread depth of R-2 tires is two times deeper than R-1 tires.
In most North American soils, R-1 and R-1W tires are the standard tread depth used. In normal soil conditions, there is little to no traction difference between a R-1 and a R-1W tire with the same tread pattern. The R-1 tire provides excellent traction and wear at a lower cost compared to an R-1W tire. R-1W tires do have a longer wear life because of the deeper tread depth and in wet conditions can provide a little more traction compared to the R-1 tire. R-1 and R-1W tread depths tires are the most common tires in the market.
When working in wet soils found in the Mississippi Delta, in any bayou region, or muck soils an R-2 tread depth tire is recommended. The extra deep tread is designed to penetrate the mud and provide traction. While these tires provide excellent mud traction, the extra deep tread depth and the very open tread pattern typically cause a lot of vibrations in the cab of the tractor when transporting the tractor on the road. R-2 tires are only recommended in the regions where operators are always in muddy soil condition.
Standard Radials, IF Radials, or VF Radials
In the past decade, the tire industry has been developing and releasing the newest radial tires marked IF and VF. Radial tires marked IF carry 20% more load compared to standard radial and VF tires carry 40% more load. The IF tires and VF tires, when inflated properly to carry the axle load, do provide a longer footprint compared to the standard radial tire, which does improve traction. The improvement is not as great as the transition from bias to radial tires, but there is up to a 5% increase in traction using IF tires.
On MFWD tractors, operators who see the greatest benefit are the ones who are carrying heavy axle loads and using inflation pressures above 25 psi. Typical conditions where the IF or VF tires make sense are on tractors that are carrying heavy 3pt tillage tools like a 12 or 16 row bedder or a 2pt mounted 24 row or larger front fold planter. With these heavy rear axle weights, dual 480/80R50 tires will need 35 psi to carry the load and in some cases, the weight exceeds the capacity of the standard radial tire. In these applications, dual IF or VF 480/80R50 tires can be used to carry those loads and may only require 23 psi. IF or VF tires are recommended on the front axle of a MFWD tractor that is equipped with a front axle suspension, uses a full rack of suitcase weights, and cannot use duals. The front axle weight of MFWD tractors set up in this configuration overload standard radial tires by 2,000 to 3,000 lbs. The same sized IF or VF tires have the extra load capacity to carry these heavier loads.
There are operations that do not benefit from the IF or VF technologies. When the MFWD tractor is properly ballasted and the correct inflation pressure on standard radial tires is 15 psi or lower, the upgrade cost to IF or VF is hard to justify. On a 200 hp MFWD tractor with rear duals used to pull a disk or field cultivator, standard radial tires will be the best fit on the tractor.
While tires are a major contributor to efficiency, operators must first make sure the MFWD tractor is ballasted correctly with the proper weight split. If the tractor is set up incorrectly, the benefits outlined will not be realized by the operator. Consult the operator’s manual to review the manufacturer’s recommendation on how to properly set up the tractor.
About Bridgestone Americas, Inc.
Nashville, Tennessee-based Bridgestone Americas, Inc. (BSAM) is the U.S. subsidiary of Bridgestone Corporation, the world’s largest tire and rubber company. BSAM and its subsidiaries develop, manufacture and market a wide range of Bridgestone, Firestone and associate brand tires to address the needs of a broad range of customers, including consumers, automotive and commercial vehicle original equipment manufacturers, and those in the agricultural, forestry and mining industries. The companies are also engaged in retreading operations throughout the Western Hemisphere, and produce air springs, roofing materials, and industrial fibers and textiles. The BSAM family of companies also operates the world’s largest chain of automotive tire and service centers. Guided by its One Team, One Planet message, the company is dedicated to achieving a positive environmental impact in all of the communities it calls home.