Maintenance – August 2009
| August 03, 2009
Double or triple the life of your tires for a fraction of the price of new
In most things, pinching pennies means some sacrifice in quality. But when you retread a tire you get equal or better the performance, warranty and longevity of a new tire for 30 to 50 percent of the cost of new.
If you’re not retreading your tires, you’re probably in the minority. Roughly half the commercial truck tires you see on the road today are retreads, says Chris Hoffman, manager truck and bus radial and retread marketing for Bridgestone Firestone. Retreading rates for off-road tires are similar.
“Even if a customer isn’t retreading, he should be selling his casings and retrieving some of that core value,” says Norm Ball, training officer at Michelin Retread Technologies. “Retreaders in the United States import between 3 and 4 million used casings every year to fill the need for retreaded tires, he says. “Fifty percent of the retreads in this country are not on the customer’s casing.”
The key to successfully retreading your own casings is to keep your new tires properly inflated and pull them before the tread gets too thin.
The minimum tread depth for off-road tires depends on the application. In soft conditions such as sand or dirt you can allow the tread to wear down to 10/32 to 15/32 inches deep, says Wilhelm Brau, general manager, Continuum Retread & Recycle Solutions. “Where there is rock, coal or sharp objects that could damage the tread, we advise them to take them off at 15/32 to 20/32 inches,” he says.
For commercial truck tires 4/32-inch is considered the limit, says Pat Demianenko, national sales manager for retreading at Goodyear. When you go below 4/32-inch you increase the risk of an unrepairable damage and when you get down to 2/32-inch you risk exposing the steel belt plies, which leads to rust, he says. Demianenko notes that it is technically feasible to retread a tire with zero tread left because most well-made tires have what he calls an “under-tread” that can be buffed. But the risk of ruining the casing goes up the thinner the tread gets, and you’ll risk your drivers’s safety and the possibility of a big fine for driving on tread that doesn’t meet DOT thickness specs.
In the past few years the technology of patching and repairing tires has improved and even cuts in the steel belts of a tire don’t necessarily disqualify it for retreading. The key is to get the tire off and in for repair immediately. If a tire with an exposed steel belt is left on even for a few days the rust will migrate into the tire and render it unusable, Brau says.
Under-inflation and overloading is also a tire killer. Insufficient air pressure will flex the tires’ sidewalls beyond their design capacity and create excessive heat. This damages the bead, shoulder and sidewall area. “The majority of the blowouts you see on the side of the road are almost all air-pressure related,” Hoffman says.
Other than monitoring air pressure and tread depth, a good tire care and maintenance program will suffice to keep your tires healthy enough for multiple retreading. Make sure your haul roads are kept clean and free of debris and rocks. Don’t mount tires on rusty rims as these can damage the beads. And fix equipment oil leaks. Tires exposed to oil spills or drips will degrade, Brau says.
Second and third retreads are common in the industry. With good maintenance four or five retreads on a single casing is possible. “But we don’t put any artificial figures on the number of times you can retread a tire,” Hoffman says.
The maximum allowable age for a casing is a hot topic, Ball says, but the consensus seems to be about 10 years. At that point some of the oils have migrated out of the rubber compounds. “Our spec on line-haul casings is seven years,” he says. “With the average line haul truck, if you retread it at seven years it’s going to be 11 or 12 years old before it comes off.”
A successful tire program isn’t about how much you pay for your new tires, Demianenko says. “It’s how much you get out of them before you throw the casing away. If you can get multiple retreads then your operating costs go down accordingly.”
Visit the dealer
Before choosing a tire retreader, visit the companies you’re considering. You want to look for several things including non-destructive testing equipment, ISO9001/2000 certification and a clean, well-organized shop. Also ask for references, particularly with fleets similar to yours. Discuss warranty, pick-up and delivery arrangements and turn-around time.
First impressions can tell you a lot, Demianenko says. “Is it clean, neat and organized? Are the people dressed in uniforms? Do they present themselves well? Are they knowledgeable about what they’re doing?”
“It all ties together. Housekeeping, safety, productivity and quality are all in the same bucket,” Ball says. “If I were a dump truck fleet owner, I’d spend half my time in the repair department,” he adds. “Ask how they handle repairs. How are they handling the cement, do they let it dry the appropriate amount of time? Ask how long they’ve been doing it and who trained them. It’s hand work, there’s no such thing as an automatic repair. You want to choose your retreader with the same thoroughness as you’d choose a doctor or dentist.”
The Tire Retread Information Bureau also recommends you talk shop with these guys. They are tire experts. They see the good, the bad and the ugly of the tire world every day. They can help you with new specs, insider knowledge and tell you about success stories other contractors have had with their tire types, different treads and management programs.
Most contractors put their new tires on the axle taking the most load or stress and retreads on the less stressed axles. For on-road trucks the steer axle gets the heaviest workout so typically the retreads will go on the trailer or drive axles. On wheel loaders the front axles bear most of the weight of the loaded bucket so retreads go on the rear axles.
This isn’t a hard and fast rule, but since you have to have some new tires to supply casings for the retread process it only makes sense to use them in the most critical positions.