Say what you will about a tire, but it won’t lie to you. If there are problems with wheel alignment, suspensions, braking or chassis, your tires will be happy to tell you, if you just take a look. They’ll tell you if they’re being run under- or over-inflated. Just read the wear patterns to find out what’s going on — and correct problems before they lead to shorter tire life and higher maintenance costs.
Irregular wear is a special problem on free-rolling axles like trailers and tag or pusher axles. “Trailer tires are on a free-rolling axle with almost no torque applied, and this creates a very slow wear rate. As such, trailer tires are prone to irregular wear,” says Roger Best, sales engineering, Bridgestone Americas Tire Operations.
Yet traditionally, trailer tires get short shrift when it comes to maintenance.
“The main reason for this is that most trailer tires are not permanently matched with specific tractors,” says Brian Buckham, general manager, product marketing, Goodyear. “Trailers are often dropped to wait for unloading and re-loading. This can create an atmosphere in which drivers don’t always pay enough attention to trailer tires.”
Add to that the fact that trailer tires on the inside of traditional dual assemblies are harder to access than their partner on the outside, Buckham says, and mismatched dual air pressures become likely, leading to mismatched rolling circumferences and wear conditions.
Interpreting the signs
As with pretty much anything in trucking today, keeping your trailer and tag axle tires in good shape falls primarily to your drivers. A good fleet maintenance program will include proper air pressure for the vehicles and loads they actually carry. And matching the correct air pressure to the load promotes even wear on trailer tires.
The effects of under-inflated tires are widely known, says Phil Arnold, field engineer, customer engineering support, Michelin Americas Truck Tires. But running more air pressure than required can promote uneven wear as well.
To catch trailer and tag tire wear, make sure your driver’s doing more than just glancing at tires and thumping them with a stick. During their daily tire inspection, drivers should:
- maintain proper tire pressure;
- monitor tread depths;
- watch for irregular wear and tire conditions; and
- inspect suspension components.
“Worn trailer tires provide visual clues that there may be an issue with trailer suspensions, shock absorbers, worn bushings, loose U-bolts, broken suspension parts, locked brakes and other problems,” Arnold explains. “If those problems are present, tires will present signs of uneven wear, including dog tracking, cupping, flat spotting, and camber. Other visual signs include sidewall cracks, tire separation, bulges, cuts, cracks, anything sticking out of the tire. Irregular wear will also develop if tires are not mounted properly and uniformly. Bent wheels, improper mounting, or flat-spotting can cause excessive runout.”
Drivers should be particularly alert for wear patterns on the tread of tires. With a little training, drivers can easily alert maintenance that a suspension or alignment issue is developing before it gets out of hand. And any time the truck is in the shop, technicians should be watching for these telltale signs as well.
“Typical trailer tires will show shoulder wear, diagonal wear and rib punch wear,” says Best. “These wear patterns typically result from maintenance issues such as not maintaining proper inflation, fifth wheel alignment and greasing.”
For starters, remember that trailers that run loaded a majority of the time historically experience less erratic or irregular wear issues. Empty, light trailers have a tendency to “bounce” when going down the road. Every time that tire bounces, it loses footprint contact with the road surface and can actually “skip” when traveling. This “skip” or loss of road surface contact will create a wear point.
Tom Clauer, corporate manager of commercial and OTR product planning for Yokohama Tire, says drivers should be on the alert for the following wear patterns:
- Wear on the inside or outside of the tread area – often on the very edge of the sidewall – is a sign of suspension or misalignment issues.
- Scalloping most often shows up as shallow cup-like areas in the tread, which indicate loose or worn suspension components such as shock absorbers. This problem can also show up as diagonal or erratic depression wear patterns that are not necessarily scalloped.
- Flat-spotting is one one of the most noticeable wear patterns in trailer tires. This is due to ill-adjusted brakes and using the trailer brakes in order to save the brakes on the tractors. Every tractor does not perform/deliver air to the trailer brakes exactly the same every time. As trailers get dropped and picked up by different tractors, drivers should make sure the slack adjusters are functioning properly or perform a simple brake adjustment each time they hook.
Once the wear process begins, Clauer stresses that it is irreversible without a maintenance fix. “Once tire rubber is gone, there is no replacing it unless it is pulled and retreaded or replaced,” he says. “Wear patterns can expand and deepen to a point where the tire become unserviceable and requires removal very quickly.”
Trailer alignment also plays a big role in extending trailer tire life, and wear patterns often point to alignment problems, “but this is not something operators or fleets often consider,” says Bridgestone’s Best.
The bottom line is simple and should be communicated to all drivers: If they notice tire wear during an inspection, immediate attention and corrective action is the only measure that will alleviate or slow these processes once they begin. Rotating the tires alone may delay a tire pull point, but will not fix underlying issues causing the wear. It’s up to drivers and technicians to observe and report wear patterns. Simple communication on this front can help your trailer tires go the distance.