By Tom Quimby
While brake issues land more trucks with out of service violations than any other component, tires and wheels are close behind.
During last year’s Commercial Vehicle Safety Alliance (CVSA) International Roadcheck blitz, 19 percent of the 11,910 vehicles placed out of service had received tire and wheel violations.
Homer Hogg, director of technical service at TA/Petro, says that proper maintenance is key in avoiding citations.
“One of the most important tire maintenance practices is to ensure the air pressure in tires matches the load being hauled,” Hogg explains. “This can be determined with load matching charts, which indicate the proper range of air pressure relative to the amount of weight the vehicle is hauling. A large part of this best practice is to check pressure levels daily to ensure they’re properly inflated. Many fleets today use tire monitoring and inflation systems to help notify drivers when tires need to be inflated.”
Auto inflators and PSI sensors can certainly play a key role in a fleet’s tire maintenance program.
“Halo and other tire tech devices have performed well on our units,” says Ryder Director of Supply Management, Nic Signorini. “Having active systems that can keep tires at proper pressure on a regular basis helps reduce tire related road calls, improve tread life, and minimize fuel efficiency loss due to under inflation. Ultimately, fleets need to do their own analysis based on their operation to determine the benefits, but under inflation is one of the leading causes of tire failure. If you start factoring in those costs and the disruption to the operation, along with improved tread life and better MPG performance, you quickly see the value in keeping tires at proper pressure which is what these devices help achieve.”
Transervice recommends keeping up with tire air pressure as often as possible and found auto inflation devices to be a good fit in their tire maintenance program.
“We use tire inflation systems to constantly monitor our tires to ensure safety and maximize the performance of the tires,” says Matt Copot, Transervice vice president of maintenance.
Whether using high-tech tire devices or a conventional air pressure gauge, Kyle Chen, brand manager of Bridgestone truck and bus tires in U.S. and Canada, says to strive for accurate air pressure readings first.
“I think it’s important to have a procedure and system in place at your maintenance yard where you can calibrate tire pressure gauges,” Chen advises. “I can’t speak to the accuracy of auto-inflation devices or PSI sensors but I’m sure they also need to be recalibrated over time. To really know what air is in that tire nothing beats a physical check of the air pressure with a calibrated tire gauge.”
Chen says tire gauges can be dropped and subjected to tough conditions in shops and should be calibrated periodically to ensure their accuracy. He suggests turning to the Tire Industry Association, or TIA, for guidance on gauge calibration and other tire-related tips.
With nearly 2,270 trucks getting sidelined last year with tire and wheel violations, what are typically some of the biggest problems inspectors find?
“Probably the most common are going to revolve around tread depth and air pressure,” Chen says. “Related to tread depth, if you run the tires too low, you may get belts or ply showing. All these lead to violations requiring the truck to be pulled out of service. Those are probably the most common. They’re going to look for any kind of tire components that are exposed either through running too low or flat-spotting, or cuts, or punctures, things like that.”
Goodyear senior product marketing manager Nick Davis says maintaining optimal air pressure not only improves fuel economy but also enhances tire wear performance and preserves casing integrity, a must for fleets that utilize retreading in their tire maintenance program. Davis also recommends that fleets avoid exceeding a tire’s load-carrying capacity and that they closely track tire performance.
“Goodyear’s Tire Optix program enables faster, more accurate collection of critical tire data like inflation pressure and tread depth, and automatically uploads this information to a password-protected cloud,” Davis says. “Tire Optix also enables fleets to download and view information in real time so they can identify maintenance opportunities and adjust their tire management programs quickly.”
As temperatures continue to rise by the day, air pressure is more important than ever.
“Cold months lead to blowouts in the first hot days of summer. Low air pressures in tires also can reduce fuel economy,” says Jim Lana, director of operations at Fleet Group. “Air pressures should be checked more than once a week. For an over the road vehicle air pressure should be checked when stopping for fuel.”
To help ensure proper tire wear and improve steering, Lana advises keeping up with alignment. But don’t stop at the steer axle. Make sure the rear wheels are aligned too, Lana says.
Fleet Group recommends rotating tires every 6,000 to 8,000 miles. Of course, abide by the tire manufacturer’s guidelines for rotation intervals.
“This will allow the tires to wear evenly and make them last longer,” Lana says.
Also, replace tires before they reach a risky tread depth of 2/32 of an inch and catch the eye of a CVSA inspector.
“Not only is it illegal, but it is unsafe,” Lana warns. “The less tread on a tire the more prone they are to objects piercing the casing causing a flat tire.”
Where the rubber meets the road
According to Bendix, about 90 percent of tire failures are owed to under inflation and nearly half of all roadside service repairs are tire-related.
“Under-inflated tires also experience greater stress and generate a higher internal running temperature, which compounds the risk of a tire blowout,” says Jon Intagliata, Bendix product manager for Tire Pressure Monitoring Systems (TPMS). “In fact, the American Trucking Associations’ Technology & Maintenance Council estimates that 20 percent under-inflation can shorten a tire life by 30 percent.”
Bendix CVS, or the SmarTire Trailer-Link TPMS by Bendix CVS for trailers, can help reduce that risk by providing real-time pressure alerts to the driver. Bendix SmarTire systems use a wheel-mounted sensor that continuously monitors temperature as well, allowing alerts that compensate for changing operating conditions, and can point to other potential wheel-end issues that lead to high tire temperatures, such as a dragging brake.
While Ryder uses the Halo Auto Inflator to help maintain proper tire inflation, they focus first on selecting the right tire for the job.
“Proper tire management starts from spec’ing the right tires when we order new trucks from our suppliers,” Signorini explain. “Making sure we get the right tires (size, load capacity, tread design, material mix) for each vehicle’s application is an integral part of controlling our tire cost per mile.”
During a scheduled PM inspection, Ryder examines their tires for air pressure, remaining tread depth, improper tread design and tire condition. Technicians verify that the tire inflation decal on the truck has the correct air pressure for the tires. PSI is recorded on a PM sheet and valve stems are checked to ensure that they have properly fitting caps.
“If the inflation pressures are within 10 psi of the specified air pressure, add air to correct the pressure,” Signorini says. “If the air pressure of any tire is 10 psi or more under the specified air pressure, the tire is to be considered ‘flat’ and marked for PM Follow Up. If pressure is above the recommended pressure and the tires are cold, bleed air from the tire to attain the correct inflation pressure.”
When it comes to checking tread depth Signorini says to measure the tread depth of all the tires on the vehicle at the lowest spot of a major tread groove closest to the center of the tire.
“Avoid the tread wear indicators or wear bars,” he says. “Record the tread depth on the PM sheet. If there is irregular wear, measure the lowest spot on the tread. If the tread depth is 4/32nds or less, mark the tire for PM follow-up. If rear drive axle has less 4/32nds than the front drive axle, rotate the drives using the X pattern for rotation.”
Regarding improper tread design, Signorini says tires found with mismatched tread designs need to be replaced. Lastly, tires should be inspected for cuts, snags, punctures, cracks, separations and other imperfections. Tread depth should be more than 4/32 of an inch for steer tires and 2/32 on drives. Refrain from using retreads and repaired tires on the steer axle.
“Inspect all tires for irregular wear patterns. Wear patterns can be caused by misalignment, loose components, and dual tire mismatching,” Signorini explains. “Look for signs of feather wear, shoulder wear on the outside shoulders (toe-in), on the inside shoulders (toe-out). If alignment, balance or worn components are found to be a problem, mark the tires for PM follow-up.
“Check dual tire assemblies for proper matching with a tire square,” Signorini continues. “Dual tire assemblies must be within 1/8-inch at the tire square. The smaller of the two tires must be mounted on the inside. If dual tires are mismatched, mark the tires for PM follow-up.”
Closer look at wheel ends
At the weigh station along Interstate 10 in Sneads, Fla., Florida Highway Patrol Trooper Bobby Simmons takes a close look at a truck’s tire and wheel.
“Good tread depth, no signs of rust and no cracks in the wheel,” he says.
Simmons also looks closely at each lug nut and grabs them as well to ensure that they’re tightly fastened.
“Another sign that you would have a loose one (lug nut) is a lot of rust around it, or if you have an elongated hole,” Simmons explains.
An elongated hole likely indicates a loose wheel that rocked back and forth enough to damage the wheel stud hole and take it out of round.
“I’ve seen that a couple of times,” Simmons says.
All the hubs on this truck check out okay. A missing or cracked hub cap can often leave greasy streaks on the wheel. Grease that eventually finds its way onto braking surfaces can also lead to an OOS violation.
As with other components, maintenance is key.
“The key here isn’t a specific part of the wheel end,” explains Erik Binns, wheel end senior product manager at Stemco. “The key is overall maintenance and monitoring of the entire wheel end system to assess the overall condition and lubricant integrity. We recommend following published recommended TMC guidelines for wheel end inspection and maintenance. Even with longer life wheel end systems, like our PPS and PPS+ systems, regular inspection and lubricant evaluation is still critical. A deep understanding of proper maintenance requirements, and product servicing procedures – and sticking to them – is the best way to keep the roadways safe, increase the efficiency and durability of your fleet, and save money in the long run.”
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