Keep tires properly inflated
Pressurized air is a structural part of the tire. In fact, air supports the entire truck. It’s as important as the steel belts, the radial cords, or the rubber itself. They are merely there to contain the air.
Air pressure keeps the tire from flexing too much. Flexing generates heat inside the tire, and excessive heat ruins tires. Without enough air, flexing can heat steel tire cords past the temperature at which rubber becomes liquid. When that happens, the tire can’t hold together. Chunks of tread start to fly off and tires delaminate.
Tire casings become damaged when running 20% or more under proper load/speed inflation pressure for any sustained period. Look at the next “gator tail” you see on the road. Chances are it has steel cords coming out. That’s not a lost tread from a recap; it’s a section of a casing that let go due to excessive heat, caused by low air pressure.
Proper air pressure depends on load and speed. A tire filled to 85 psi may be safe when running empty, but it could need 100 psi to carry a full load. Every tire manufacturer has load-speed-inflation tables for each of its tires (available from dealers).
Tire pressure monitoring systems alert drivers or mechanics at each wheel end or using dashboard monitors. Inflation systems help trailer tires maintain air pressure, even after minor damage.
Find a good balance
Much of the pavement pounding seen from loaded and empty trailers occurs because an imbalance wants to pull the tire off the pavement, then slam it back down as the tire rotates. Imbalance causes uneven wear.
Several devices help maintain balance with weights carried in viscous fluid, moving freely within a circular devices bolted to or between wheels. Other products use granular material or fine glass beads inside the tires. The added masses automatically seek the proper position to balance the rotating assembly.
Match tire size
Keep tires in a dual set matched as closely for size as possible. One-quarter inch radius difference is the recommended maximum difference, but if you can, keep tire diameters matched to less than 1/8 inch. Since the two tires are bolted together at the wheels, they turn the same number revolutions per mile. Because their diameters differ, they will travel different distances resulting in scuffing and uneven wear.
At a 1/4-inch difference, the larger tire could carry 600 pounds more than the smaller one. It will also wear out faster. Both will wear unevenly. Note: Even if perfectly matched by size, inflation differences will affect wear and load. With a 15 psi difference and a full load, the higher pressure tire will carry 500 pounds more than the other.
Establishing your own tire maintenance program is easy to do, and it will increase the use you get from your tires. If you maintain your tires well, you can have your own casings re-treaded. That way, you get a retread with a known history. A good casing, kept inflated, aligned, and balanced, should last two or three retread cycles, giving two or three more lives with new treads. Even if you don’t want to run retreads, a well maintained casing has significant trade-in value.
Paul Abelson is a former director of the Technology and Maintenance Council (TMC) of the American Trucking Associations, former board member of Truck Writers of North America, and active in the Society of Automotive Engineers. E-mail firstname.lastname@example.org.