Increased Deflection Agricultural Radial Tires Following the Tire and Rim Association IF, VF, and IF/CFO Load and Inflation Standards

Abstract.

Limiting soil compaction has been the focus of tire and track manufacturers as axle loads have increased with larger agricultural equipment. Track manufacturers are increasing track widths and lengths, and adding more mid-rollers to increase footprint area in the attempt to reduce contact pressures. In the past decade tire manufacturers have increased the diameter and width of radial tires to increase the air volume chamber while maintaining the same deflection and keeping operating inflation pressures below 210 kPa (30 psi). In the mid-2000s, the tire industry was close to the maximum allowable diameter of the tire and width regulations of various countries prevented the tires from getting wider. To carry the heavier loads the operational pressures of the tires had to be increased from 210 kPa (30 psi) to 280 kPa (41 psi). The increase in operational pressure could be designed into the tire, but the higher operational pressure increases the contact pressure the ground experiences when the tire traffics the soil. In dry soils the higher contact pressure does not noticeably damage the soil structure. In moist or wet soils, the higher contact pressures reduce pore space, damages soil structure, and cause soil compaction. To help reduce the tire‘s damage to the soil by lowering inflation pressure, new radial tire standards were developed by the tire industry. These new standards allow the tire to deflect more than a standard radial tire. The IF, VF, and IF/CFO standards increase the load-carrying capacity of the radial tire without increasing the inflation pressure.