The Importance of Proper Steer-Axle Inflation
Proper steer-axle inflation can be the difference between completing a trip safely or ending up in a bad accident. Inflating tires on a 12,000-pound steer axle to 100 psi may have been okay 20 years ago, but it is not enough anymore. According to various manufacturers’ load and inflation tables, a standard profile 11R22.5 load range G tire needs 105 psi to get beyond 6,000 pounds load carrying capacity. Low-profile 22.5-in. tires would need 110 psi. In prior years 12,0000 pounds was considered the standard steer axle weight, but with aerodynamic packages, emissions controls, set-back axles, etc, the extra load on the steer tires must be looked at. Tires do not respond well to under-inflation.
To increase the load capacity of a tire you can do two things.
- Increase the volume of air in the tire.
- Increase the pressure of the air in the tire.
The load range rating of the tire ensures that it can carry the weight at a given pressure while maintaining the same footprint and amount of sidewall flex. Tires are designed to meet certain government and industry standards.
What Is the Correct Load Range and Inflation Pressure for Your Steer Axle?
There is no correct answer for what the correct load range and inflation pressure should be for your steer axles. To estimate the correct load range and inflation pressure, have your drivers’ axle-weigh each load over a period to get an idea of what your steer axle loads are. Do not forget to account for fuel on board. Once you have determined your steer axle loads, inquire the axle loads with your tire supplier.
Watch Your Tires
A tire does not go from being properly inflated to a blowout unless you hit something on the road. It is said that 80% of blowouts could be prevented if tires were kept properly inflated. Tires are found to lose 2% of their inflation pressure, by volume, over a 30-day period, regardless of the casing, valve stem, and tire bead being in perfect condition.
It is uncommon to find a perfectly sealed tire/wheel assembly, so the actual rate of seepage could be as high as 2% per week. Steer tires do not have that 30% margin we build into drive and trailer tire inflation pressure.
Road Speed and Inflation Pressure
Road speed does have an impact on inflation pressure. When a tire manufacturer rates a tire for 75 mph, it assumes the tire is properly inflated. Steer tires run close to the margins where proper steer-axle inflation pressure becomes critical. Five to 10 psi makes a difference with steer tires. Always make sure you have the correct size and load range of tire on your steer axles. Inflation pressure is critical.