For most fleets, three key factors combine make maintenance for trailer tires challenging.
1. There are generally far more trailer wheel positions than steer or drive wheel positions.
2. Because trailers swap from one tractor to another, they tend to get less attention from drivers than tractor tires.
3. Trailers may be off-site and out of reach from fleet maintenance personnel for extended periods.
These tips can help extend trailer tire life and save time and money.
TIRE SELECTION
Proper tire selection puts fleet maintenance personnel in a good position to get the most from their tires. Since irregular wear is a common phenomenon with trailer tires, most new trailer tires feature shallow tread depths.
More tread may not mean more miles. Deeper treads are more prone to irregular wear, so an 18/32” tread is not likely to deliver 50 percent more miles than an 11/32” to 13/32” tread pattern.
Straight ribs are also less likely to generate irregular wear. In linehaul use, defense/decoupling grooves are very effective at delaying the onset of irregular wear. Therefore, unless the application is high-scrub, choose a shallow, straight pattern with a defense/decoupling groove.
In high scrub applications, most fleets are successful with deeper rib tires that do not feature a defense/decoupling groove.
It is also common for users to “run out” a steer or drive tire on the trailer position. This is a good way to get more use out of a steer or drive tire, but be sure that tires in a dual assembly are well-matched for overall diameter (within 1/4”).
Fleets that track wear rates will notice that “runouts” may not perform as well as trailer tires, but since the tires delivered useful miles in the steer or drive position, it can be a useful strategy.
AIR PRESSURE
Correct pressure is a critical component to improving trailer tire performance. Trailer tires are far more likely to be improperly inflated than other axle positions, and the variance can be either high or low.
Low pressures primarily occur through negligence and can lead to casing degradation and road calls. High pressures – which are far more common than low pressures – primarily occur through poor pressure spec choices and lead to fast or irregular shoulder wear and decreased damage resistance.
The starting point for a fleet’s pressure specification should be a load/inflation table, not the sidewall marking. These are available on most manufacturer websites.
Yokohama Tire, for example, features a web-based tool for easily calculating tire pressures (www.yokohamatruck.com/commercial/tire-tools/inflation-pressure-calculator). In a typical 80,000 lb, five-axle combination, trailer tires can carry their load at relatively low pressures: 75 to 80 psi. Yokohama recommends adding another 10 psi to compensate for air loss between checks.
If fleets routinely see irregular shoulder wear and have a trailer tire inflation spec of 100 or 110 psi, overinflation may be the cause. Fleets that are seeing the symptoms of overinflation, but are uneasy about drastically lowering pressures, can run trials at 10 psi increments and look for improvements rather than immediately dropping their spec by 30 psi.
Fleets with considerable empty mileage have the most to gain by lowering pressures to the minimum for their load situation.
REGULAR INSPECTION
Regular inspection is necessary to ensure that maximum performance is obtained and road calls are reduced. A strategy employing “eyeballs and air gauges” will spot most trouble before it becomes serious.
A reliable, calibrated pressure gauge is the only way to accurately check tire pressures. Tires should be within a few psi of the fleet spec and never less than the minimum to carry the load. Tires in a dual assembly be within 5 psi of their mate.
Tires be checked when cold and never adjusted for pressure when they’re hot.
A visual inspection can find tire damage, such as cuts and punctures, which could cause a road service call if left unaddressed. Similarly, looking for irregular wear patterns can extend tire life by identifying alignment issues or other trailer problems that cause tires to wear faster than they should.
Pat Keating is the senior manager of technical engineering for Yokohama Tire Corporation (www.yokohamatire.com), the North American manufacturing and marketing arm of Tokyo, Japan-based Yokohama Rubber Co., a global manufacturing and sales company of premium tires since 1917. Servicing an extensive sales network throughout the U.S., Yokohama Tire Corporation offers a complete product line that includes tires for high-performance, light truck, passenger car, commercial truck and bus and off-the-road mining and construction applications.
