by Peter Corbett
Bus and motorcoach operators have little control over fuel costs, but they do have savings options when it comes to tires for their fleets, which often are the second most expensive item in their operating budgets.
That’s why many operators rely on retread tires, in which new treads are added to an existing tire structure, said David Stevens, managing director of the Tire Retread and Repair Information Bureau. These remanufactured tires can be more than 35 percent cheaper than a similar new tire and have important environmental advantages.
However, the public has a common misconception that retread tires are less safe and more likely to fail than new tires, leaving a trail of shredded treads on the nation’s highways, Stevens said.
“I hate to have this perception that retreads are any less safe or reliable,” he said. “Retreads are used every day by buses and ambulances and fire trucks, and they’re just like a new tire.”
Close to 80 percent of commercial jets operate with retread tires for the landing-gear wheels, Stevens added.
State and federal studies indicate that when shredded rubber hits the road there’s no evidence retread-tire failures are more common than new-tire failures. The most recent federal study, a 2008 report by the National Highway Traffic Safety Administration, examined 300 discarded tire casings from truck stops and 1,200 tire fragments collected along interstates at five locations.
“The analysis… found that the proportion of tire debris from retread tires and (original equipment) tires is similar to the estimated proportion of retread and OE tires in service,” said the NHTSA report.
In other words, there are more retread tires in use for commercial trucking and bus fleets than new tires, so there was a proportional number of tire fragments from each category.
The 200-page NHTSA study found “available crash data shows that vehicle crashes related to truck tire failure and truck tire debris are very rare events that account for less than 1 percent of traffic crash involvements.”
A 1999 tire-debris study by the Arizona Department of Transportation concluded there was no basis for a policy to restrict retreads or other specific types of tires.
The U.S. Department of Transportation only restricts retread tires from use on the front wheels of buses.
New and retread tires most commonly fail because they are under-inflated, overloaded or are damaged by sharp objects or other road hazards, said Stevens, a 10-year spokesman for TRIB, the industry trade group based in Falls Church, Virginia.
There are nearly 725 retread tire plants in the United States, most of them affiliated with major tire brands including Bridgestone, Continental, Goodyear and Michelin, he said.
Retreading starts with visual inspections of tires. A voltage tester detects nails or other metal. An X-ray machine spots defects or damaged steel belts that are otherwise undetectable.
Tires deemed reusable are stripped of the old tread and a new tread is added. Vulcanization—a process involving heat, pressure and curing time—bonds the layers of rubber together. After final inspections, the tires are painted to appear like new tires and sent back to operators of bus and truck fleets.
Tires can go through the retreading process a half-dozen times or more, depending on the type of use on buses or trucks, Stevens said. The tire cost savings is significant for operators, he said, and the use of retreads keeps millions of tires out of landfills while using less than one-third the amount of oil needed to manufacture new tires.