HILTON HEAD, S.C.—Tires long have been the biggest maintenance cost for truck fleets, and managing those costs is the difference for most fleets between profit and loss, according to Al Cohn, director of new market development and engineering support for Pressure Systems International.
In 2011, average prices for commercial tires increased about 50 percent, Cohn told the audience at the 30th annual Clemson University Tire Industry Conference at Hilton Head from April 23-25.
“Some tires rose 60 or 70 percent,” Cohn said. “Big fleets paid a little less, but the little guys really got hurt.” However, commercial tire prices were stable in 2012 and 2013, and have been so far this year, he said.
Because of high prices, truck fleets take tires very seriously, according to Cohn. For a typical 18-wheeler, all new tires on all wheel positions will cost $7,000 to $9,000, he said. Even with retreads on the drive and trailer positions, a full set of tires will cost $5,000 to $7,000, he said.
Fleets seek the help of their tire dealers and suppliers to optimize tire use and reduce costs, according to Cohn. “Fleets are in the business of hauling freight,” he said. “They always want to tap into the knowledge base of the tire professional.”
On a typical linehaul truck, the target mileage before removal is 300,000 miles for drive tires, 200,000 each for steer and trailer tires, Cohn said. But any number of factors can cut down on the mileage truck fleets obtain, he said.
Those factors include makes and models of tires and vehicles, routes, speeds, vehicle alignment and tire pressure maintenance, Cohn said.
One factor that is sometimes overlooked in truck tire mileage is load. “The lighter the load, the better the tire mileage,” he said. “The tires on a truck hauling potato chips last a lot longer than the tires on a truck hauling bowling balls.”
Another often overlooked factor in truck tire mileage is the driver, who can affect tire mileage by as much as 35 percent, Cohn said. “There's a direct correlation between the age and experience of the driver and the tire mileage you get,” he said.
The biggest mistake most fleets make is not offering driver training regularly, according to Cohn. “If you ask a fleet operator, "Do you offer training?' he's likely to answer, "Sure—a 20-minute class the first day,'” he said.
“Training programs offer wonderful opportunities for tire manufacturers and dealers to work as a team with their fleet customers,” he said.
A successful truck fleet tire program, according to Cohn, means paying attention to many factors. These include choosing the best tire makes and models for the trucks in your fleet; choosing an optimum tire pressure specification based on the worst-case scenario for each axle position; and frequent tire inspection.
Much of a successful fleet tire program revolves around retreads, Cohn said. “A retread is one-third of the price of a new tire, so you need to protect that casing to make sure you can retread it,” he said.
Precise targeting of tread depth for tire removal—the legal limits are 4/32 inch for steer tires and 2/32 inch for drive and trailer tires—will protect the casing from damage, Cohn said. Also, the gathering and analysis of information about tire mileage and performance will help fleets determine how many retreads they can get out of each casing, he said.
Tires can lose air through leaking valve stems or sidewall damage, according to Cohn. Depending on the tire inner liner compound, a truck tire can lose 1 to 3 psi per month through osmosis, he said.
Tread punctures are also a problem for truck tires, Cohn said. “Truck tires typically don't get blowouts,” he said. “Instead, they develop a slow leak through which they can lose 1 to 3 psi per day.”
In the U.S., tire air pressure is usually better on the left side than the right, Cohn said. “It was exactly the opposite when I worked for Goodyear in England.” The right rear inside trailer tire usually is the most underinflated on an American truck, he said.
A recent survey of truck fleets showed that 62 percent use automatic tire inflation systems to maintain proper air pressure; 29 percent use tire pressure monitoring systems; and 14 percent use tire sealants. “Twenty years ago, the result would have been zero,” Cohn said.
Fuel-efficient tires represent a major cost savings for fleets, overriding any loss in tire mileage, according to Cohn. “If a fleet can go from 6.5 to 6.6 mpg, it will save millions of dollars,” he said.