Fore!

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As you may have read last month (“Boosting MPG: No Silver Bullet,” CCJ, June 2007), there are many myths about engine-related products and practices claimed to produce an increase in fuel economy. Thanks to our friends at Goodyear, we now offer some other misconceptions, this time regarding tire wear and performance.

According to Tim Miller, Goodyear’s marketing communications manager for commercial tires, it’s tempting to look for any edge to improve tire performance and keep costs down. But, he adds, questionable procedures actually could reduce tire performance and void warranties. Consider the following examples:

Myth: Golf balls in tires help improve balancing. Wrong, says Goodyear. Any unbalance condition in a steer tire assembly (tire plus wheel) can lead to vibration that the driver feels in the steering wheel. Many drivers believe that using balance material inside a tire will help reduce tire/wheel vibration. Proven products are an OK bet, but golf balls are a stretch. They tend to compress into a cube pattern, says Goodyear, which can damage tires’ inner liners.

Myth: Overinflating tires will allow you to carry heavier loads without reducing speed. Busted. Tires are designed to run at a specific inflation pressure. Overinflation reduces a tire’s footprint and places more weight on the middle of the tread. Not only will this reduce a tire’s life, but ride quality, stability, safety and traction all can be compromised.

Myth: Deeper tread depth guarantees better treadwear. The reality, says Goodyear, is that too much tread depth will cause the tread lugs to compress and squirm, which leads to premature removal because of fast and uneven wear. For every truck, application and load bearing requirement, there is a specific tread design and depth that will provide optimum tire life and the lowest possible cost per mile. More is not always better.

Myth: Retreads wear faster than original tire treads. Not necessarily. Reputable tire manufacturers view the original tires they make and the retreads they offer as a system. Goodyear’s position, for example, is that a retread should begin with a casing that is rugged and able to offer a long life through multiple retreads. Goodyear says its retread wear rate is comparable to that of its new tires.

Myth: “Road alligators” all come from retreads. For many people, perception is reality when it comes to tire debris on the road. Motorists see strips of tread and conclude that a retreaded tire must have come apart. It’s this perception that has led to several studies, which invariably have found that approximately half of tread-debris samples came from tires that had never been retreaded.

So what’s the main cause of these rubber reptiles on our roads? It’s simple inattention to inflation pressure. If tires are overloaded, or run underinflated (20 percent underinflated is considered a run-flat by tire manufacturers), the chances of tire disintegration are maximized.

The reason is that steel tire belts, like wire hangers and paperclips, generate heat when bent back and forth. And heat is the root cause of many a tire’s demise. Also bear in mind that mismatched tires on duals also can be culprits, since one tire is doing more work than the other.

And don’t assume that evidence of underinflation damage is found only on the road. A precursor to total tire disintegration from underinflation often is a circumferential break in the mid to upper sidewall, exposing an even line of broken cords. A “zipper failure,” as it’s called, can happen in the shop, when an already weakened tire is being inflated. The air pressure becomes too great for the cables to hold, and the entire area ruptures violently.

Releasing energy on the football field or golf course is a good thing, but let’s keep trucks and trucking safe.