By Paul Abelson
Right after drivers and equipment operators, tires represent the largest expense for truck fleets. “Virgin” tires for snowplows, dump trucks, and other heavy equipment are quickly approaching $500 each.
Tire prices are directly linked to oil prices, since about 22 gallons of oil go into each new tire. Reusing casings, the structural body of the tire, saves 15 of those 22 gallons. The remaining 7 gallons represent tread that wears out in use, and intermediate layers between the casings' cords and the tread layer. In a retread, they are ground off to ensure proper geometry, then replaced.
Even with the time, labor, and equipment needed to prepare and retread tires, the cost can be 50% less than new ones. Tires are designed to be retreaded as many as two or three times, assuming they're properly used and maintained.
Preparing for retreads
The best candidates for retreading are your own tires, provided they have been well maintained, inspected periodically, and removed with at least 4/32 inch of tread left. Federal Motor Carrier Safety Regulation 393.75 requires tires to be replaced at a legal minimum tread depth of 2/32 inch (4/32 inch for steer tires).
Tire management also requires close attention to air pressure, tire balance, wheel alignment, and avoiding overloading. Adequate air pressure is critical to casing longevity. When air pressure is substantially low, heat begins to destroy tires.
Without enough support, the tire casing flexes more than it should and generates heat. If the tire's steel cord flexes enough, it melts the bonds that hold tire components together. That — not faulty retreading — is the primary cause of “road gators,” the strips of tire tread found along roads.
|THE GOOD, BAD, AND UGLY
Not all retreads are created equal.
Working with the right vendor can help you avoid buying a “Maypop.” This is a tire “that may pop in 30 minutes or 30 miles,” according to Harvey Brodsky, director of the Retread Tire Association.
A good retread is made from a casing that has not been abused during its previous service life. It is thoroughly inspected using the latest industry-accepted methods, both before and after retreading. The tread is matched to the application for which it is intended. This retread will provide good service through several lifetimes.
A bad retread is given only a visual inspection. It is capped with a generic tread and put on the shelf for sale. You may be happy with it, but it could have defects that lead to early failure.
The ugly retread comes from the retreader with little or no inspection and qualification procedures. Some spray paint makes it look good, but underneath it could be a disaster.
Underinflation is the reason for most tire failures, according to a recent National Highway Traffic Safety Administration study that physically examined thousands of tread strips. About three-quarters of the cast-off treads were from virgin casings. (If you see steel tire cord in a strip, it is from a casing, not a separated tread. There is no cord in the tread.)
Overloading tires by carrying too much sand or salt can lead to casing failures. Also, when a driver tries to “limp in” with a flat in a set of duals, it doubles the load on the remaining tire. This will quickly ruin the good tire.
Improper alignment will wear a tire unevenly, shortening its service life. But if cords aren't exposed and enough rubber remains, the tire can be retreaded. In fact, most damage, if quickly and properly repaired, will not prevent retreading a tire. A good retreader will determine a tire's suitability for retreading.
Choosing a supplier
The best way to start a long-term fleet tire program built around retreaded tires is to establish a relationship with your supplier. Both the Retread Tire Association and the Tire Retread and Repair Information Bureau advise visiting the plant of each supplier you are considering.
Observe and compare their nondestructive testing methods and equipment. Ask the following questions:
- What happens to tires when they are brought in?
- What happens to tires that are rejected?
- Do they follow industry recommended practices for retreading?
- Can they provide references? If so, call them.
- What is their rate of tires returned under warranty vs. the number of tires sold? All good retreaders keep accurate records on returns.
Don't hesitate to find another vendor if the answers aren't satisfactory.
Finally, prices are important, but only in the final stage of decision-making. High-quality products are most important, followed by services that help you control total ownership costs.
— Paul Abelson (firstname.lastname@example.org) is a former director of the Technology and Maintenance Council (TMC) of the American Trucking Associations, a board member of Truck Writers of North America, and active in the Society of Automotive Engineers.