Extending the life of truck tires has never been more important.
Between price increases and diesel over $5 a gallon, operating cost stress is impossible for fleets to ignore. Every step must be taken to maximize the life of tire casings in order to achieve the lowest possible cost per kilometer. Maintaining proper inflation plays a major role in retreadability, perhaps the most important. Nothing turns a $500 truck tire into a twisted mess of sidewalls and steel like under-inflation. Gator season has also officially arrived, and alligators love the heat that comes with overloaded tires because tire pressure hasn’t been checked or adjusted.
Another reason for an underinflated or overloaded tire is a puncture which breaks the inner liner, which is a thin layer of special rubber inside a tubeless tire that is, for the most part, airtight. . If there is a hole in the inner liner, the tire will begin to lose air pressure. In almost all cases, an object causes a violation. Tire guys love to collect stuff they’ve pulled from flat tires; my personal favorites were a spark plug, an animal bone, and a rake.
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Minor punctures caused by nails, screws and other small objects are easily repaired virtually anywhere. Modern puncture repair equipment and materials make it easy to remove the damage caused by the injury, fill it with rubber so that the steel belts are not exposed to moisture, and install a repair unit on the inner liner to seal the breach. Thousands of puncture repairs are successfully installed every day. In almost all cases the leak is stopped and most of the time the casing can be saved.
When punctures are small (3/8″ or less) and located in the center of the tread, the standard plug and patch is installed. Smaller shoulder injuries (5/16″ or less) use the same plug-and-patch process, but a larger repair unit is required so the reinforcement plies do not end in the flex area of the sidewall . When a tread or shoulder injury is outside the repairable limit or the damage is in the sidewall, a section repair is required.
The term “section repair” refers to the type, size, and location of the injury. In the tread wounds up to 1.5″ can be repaired, while the repairable limits of sidewall wounds vary by size and can be up to 5″ long and 1 5/8 inches wide. In both cases, all damaged body plies and belt cables are removed and recut with solid rubber. Raw rubber is applied to the vacuum and then cured in a retreading chamber or with a device that applies heat and pressure directly to the repaired area. A large reinforced repair unit is installed inside the tire to seal the inner liner and provide additional support around the injury.
When properly installed, a section repair restores the casing to its original condition so it can be considered for retreading when the tread wears out. Section repair costs more than a puncture repair because it requires special equipment and tooling in the hands of a technician with a higher level of skill. A section repair also requires more time to remove the damaged material and harden the repair to become part of the tire.
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It’s big business in the off-road and earth-moving industries because tires are too expensive to just throw away when the injury is too big to fix in the field. Section repairs are widely accepted because they can withstand severe service in mining and construction applications. During a major shortage years ago in a few sizes, companies would literally dig up old damaged tires so they could be repaired and put back into service. Desperate times called for desperate measures.
We haven’t reached that point yet in the commercial truck tire space, but the cost of replacing a new tire shows no signs of going down. Likewise, the value of casing preservation is expected to increase as retreading becomes a more important part of every fleet tire program. The technology of tools, equipment and materials has improved over the years so there is a history of performance and safety with section repairs not to be overlooked. Section repairs save casings, and casings save money when part of a retread program. It’s a simple equation that adds up to lower tire costs.
Kevin Rohlwing is senior vice president of training for the Tire Industry Association. He has over 39 years of experience in the tire industry and has created programs to help train over 180,000 technicians.