Tires: When Rubber Meets the Road

Unsightly and potentially dangerous, the large chunks of tread from heavy-duty tires at the roadside have elicited more than a few negative comments over the years about “truckers and those cheap re-treads they use.”

But that’s largely an erroneous assumption, according to the Highway Tire Debris Task Force of The Maintenance Council of the American Trucking Associations. The task force was created to help educate fleet supervisors and owner-operators about proper tire care and to explain to regulators and legislators the true cause of most tire debris on the road: poor tire maintenance generally, not specifically any inadequacy with retreads.

The TMC task force analyzed tread collected from 13 stretches of highway around the U.S. in 1995 and found that under-inflation was the major cause of premature tire failure, sometimes compounded by undetected cuts, punctures or other road damage.

Nor is there necessarily more rubber on the road now than in years past. The same 13 test locations were screened again last year, and while the gross amount of tire debris collected was up by 28% (attributable in part to the jump in trucking activity), the proportion of debris from retreads versus first-generation tires was about the same: 87% retreads, 13% from new tires. But that doesn’t really reflect as poorly on retreads as you might think.

“The proportion of retreads that were adjudged to have failed prematurely because they were improperly retreaded-bond failure, missed nail holes, tread ‘list’ and the like-was just 8% in the latest study,” explains tire-management consultant and task force chairperson Peggy Fisher. “Evidence of under-inflation was widespread, and if you under-inflate a tire, it will fail prematurely, regardless of whether it’s a new product or a retread.”

There may be other factors at play, such as high road speed. The task force and the U.S. National Highway Traffic Safety Administration plan to study the effects of speed on tire life at the Transportation Research Center in East Liberty, Ohio. It’s hoped that these tests will provide more insight on things like the possible difference between a new tire and a retread in how much abuse from under-inflation they can generally handle. “Does a retread fail at 60 psi while a new tire could last down as far as 40 psi? These are the kinds of things these tests will hopefully clarify,” Fisher says.

Meantime, Fisher offers some general tips you can use right now to help you reduce the amount of rubber your vehicles leave on the highway.

TEACH YOUR DRIVERS

“At the TMC general meeting in March, we discussed feedback from a questionnaire we’d sent to fleets last year, asking how many en-route emergency delays they were experiencing related to tire failure, and problems with tire maintenance,” Fisher reports.

“Of the five top reasons given, four related to drivers: lack of attention to proper pre-trip inspections; lack of motivation to monitor tire inflation/condition; lack of education in how to do it properly; and a sense that drivers just didn’t feel that this was their job.

“There were many comments about drivers still just ‘bump-checking’ tires and not using pressure gauges, and so forth.”

The task force has distributed brochures about tire care to fleets and truck stops, and offers mail-order sales of tire-inflation gauges, valve caps, tread-depth gauges, and the like at reasonable prices. It also provides stickers for the dashboard to remind drivers to properly check their tires.

SCHEDULE INFLATION CHECKS

Fisher advises fleets to formalize the way they maintain tire air pressures. Most tire companies recommend tires be checked for correct air pressure once a week-rarely possible, she says. Try using the tractor PM as the interval for checking tractor tire pressures, and using the trailer PM or pick an arbitrary interval for checking trailer and dolly tire pressures.

A good practice is to install a tire inflation update decal in a visible location on each vehicle, so that anyone can tell at a glance that a vehicle’s tires should be checked and know what the inflation pressure should be.

Pay special attention to trailers. The 1998 TMC task force study revealed that 71% of the tread fragments collected had a rib pattern, indicating that they likely came from trailers rather than power units.

DO IT RIGHT

Accurate tire gauges should be used to check pressures on all the tires on the vehicle, including the inside duals. (Inflate-thru valve caps make this chore easy.) Clubs, or “tire Billys,” used to hit tires to see if they are flat, don’t count as proper tools for checking tire pressure. You need actual tire pressure numbers to discover problems.

For example, a tire 10 to 15 pounds below others on the vehicle is losing air and should be removed and inspected before it fails on the road.

Tire inflation pressures should be checked when the tires are cold, preferably early in the morning or before the vehicle is driven.

Once the vehicle has been out on the road, it may take three to four hours for the tires to cool down. Since heat increases air pressure (10 to 15 psi in normal operations), never bleed air from hot tires, as the tires will then be underinflated.

And, of course, during installation of the tire/wheel assembly on the vehicle, make sure the inside valve stem is accessible.

This can make all the difference in getting air to that inside tire.

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GOOD ADVICE

Truck tires lose two pounds of pressure a month just by air permeating the inner liner and going through the tire. Air can also escape between the bead and wheel, as well as through improperly tightened valves, torn rubber valve grommets, or valve cores that have been blocked open by dirt and ice. Then there are nicks and cuts to watch for. Fisher says one large fleet she knows uses a service truck and a dedicated tire man who works Saturdays through Wednesdays, visiting every vehicle on the yard, checking and adjusting air pressures and removing unserviceable tires. It has a cost, but also a tremendous payback in terms of reduced road calls, improved tire performance, and fuel economy. And the fleet doesn’t have to rely on drivers to check tire pressures at PM time.