Heavy Duty: In the Groove

Are you retreading too soon? You may be wasting usable tread, and throwing money down the drain.

Okay, everyone in the fleet transportation industry understands how important it is to hang onto good drivers. Some experts estimate that it costs a company in excess of $10,000 to get a driver behind the wheel of a truck, so it makes sense that fleets would want to do anything they can to pamper their drivers and get maximum return out of that investment. They might even start to swap tires out before their time, just so drivers don’t complain about a loss of traction.

They might, but according to industry experts, they’d be making a costly mistake.

According to Doug Jones, customer engineering support manager, Michelin North America, the lowest tread depth allowable on heavy-duty steer tires by the Federal government is 4/32nd of an inch, while 2/32nds of an inch is allowable on heavy-duty drive tires.

“But what we find is that most fleets will pull their tires for retreading at about 8/32nds to 10/32nds,” he says. “That means that you’ve got about 6/32nds to 8/32nds of inch of useful tread that is buffed off when the tire goes to the retreader.”

In other words, fleets are losing tire life, and losing money in the process. “How much money they’re losing depends on driving habits and applications,” Jones explains, “but if a new tire comes with 30/32nds of tread depth, and they’re taking them off for retreading at 10/32nds, they’re losing about a third of their usable tread.”


First off, Jones recommends that all fleets have a tire management program. As part of that program, he says, the fleet maintenance manager should decide on a casing policy. “How they want to use that casing after its first life determines when they pull it,” he says, but it’s easy to make an error in judgement. “Their thinking is that they’re protecting the casing (in setting short periods for retreading), but, over the years, casing endurance has increased.”

It’s common practice, of course, for fleets to buy new steer tires, then retread them and move them to a drive or trailer position. Many of those fleets will then retread the casings a second time, and return them once again to a drive or trailer position.

“Some will retread the casing for as many times as they think they can get useful life out of it,” Jones observes. “Some will only retread the casing once, and they may be short-changing themselves there, too. But one of the reasons they’ve done this in the past is that when you get a casing that gets down to about 4/32nds tread depth, they become more susceptible to stone drilling.”


Unfortunately, few drivers are as knowledgeable about tires and casings as Jones is, and that’s where problems can arise.
Perception, as they say, is reality, and if a driver perceives that a tire is lacking traction, he or she is likely to make an issue of it.

“A lot of fleets develop their practices based on driver satisfaction,” Jones says. “The drivers, when they do their pre- and post-trip inspections, they see the tires wearing down, and they become concerned.

“That’s one of the main reasons tires are pulled early,” he explains. “The driver is saying, ‘This tire doesn’t have any traction; it broke loose, and it’s getting down to a point where I don’t think it’s safe.’”

Again, the legal standard for a roadworthy tire is 4/32nd-inch of tread on the steers and 2/32nd-inch of tread on the drives, but when the tread is that shallow, looks can be deceiving, and unsettling.

“When traditional tires start to wear down, a lot of the sipes will disappear,” Jones explains. “If there’s an open shoulder, the appearance of the open shoulder will disappear and it will appear to have a solid shoulder. The appearance of a loss of traction is there, but it’s not necessarily true that a visible groove means better traction.

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