Tire Myths...and Reality

"Black and round." If that sums up the bulk of your knowledge about tires, you could be missing out on some key facts.

By Rik Paul

Photography by the Author

Myth: I should inflate my tires according to the pressure indicated on the tire sidewall.

Fact: The handwriting's not on the wall--the tire sidewall, that is. Molded into the sidewall is the tire's maximum inflation pressure, not the manufacturer-recommended pressure. For normal operation, follow inflation pressure recommendations in the owner's manual or on the vehicle placard located in the glovebox or on the door post. Myth: A tread pattern is needed to provide great traction on dry roads. Fact: A racing slick--a tire without any tread--provides the ultimate in dry traction due to the maximum amount of rubber touching the road. A tread pattern, with its groove voids, actually compromises this adhesion capability on dry roads. The role of tire tread is to act as a squeegee on wet roads to remove water from under the tire and channel it through the grooves for improved wet traction.

Myth: Performance tires wear out faster because of the sticky compounds.

Fact: Performance tires may wear out faster than conventional family-car tires; however, tread rubber polymers aren't the culprits. In fact, new polymers and ultratensile steel constructions make performance tires last longer than ever. Industrywide, performance tires average about 45,000 miles in tread life, similar to the figures for family-car passenger tires. Fast wear usually is due to high-horsepower vehicles fitted with the tires and aggressive driving. Jackrabbit starts and quick stops can shorten the life of any tire.

Myth: Wide tires provide better traction under all weather conditions. In fact, putting oversize snow tires on a car delivers better snow traction.

Fact: The opposite is actually true. Wide tires tend to "float" on deep snow, and the tread lugs never have a chance to "dig" through to the road surface to gain traction. Narrow tires are a better option in deep snow. The tire acts similarly to a knife cutting through butter; the blade works best when using the narrow edge to push through the butter rather than the wide flat side of the blade.

Myth: All-season tires are so good that winter tires are never needed.

Fact: In some parts of the country, this may be true, but if you live in the northernmost states or in Canada, the traction provided by winter tires can't be beat. Winter tires reign supreme in rural areas where snow remains on the road for days. They provide 25-percent-improved traction in deep snow over all-season tires. Metal-studded tires deliver up to 40 percent greater traction on hard-packed snow and ice over all-season tires, but many locales have restrictions regarding the use of studs.

Myth: Never rotate tires from side to side, only front to back.

Fact: Radial tires can be crossed from side to side in the rotation pattern. The old front-to-back rule applied to bias ply tires. Regular tire rotation--every 6000 to 8000 miles--promotes more uniform wear for all tires on a vehicle. (Goodyear recently designed a light-truck tire system that requires no rotation; the Wrangler RF-A provides a rear tire with a different tread design from the front tire).

Myth: Put your new tires on the drive-wheel position to get the most traction.

Fact: This is only true on a rear-drive vehicle. In all cases, install new tires on the rear axle. Most tire buyers purchase new rubber for the drive-wheel position to get the most traction; however, by doing so they transfer most of their traction capabilities from the rear and make it susceptible to oversteer. The vehicle's rear will fishtail and swing out in fast cornering or emergency maneuvers.

Myth: Sticking your fingernail in the tread can help you pick the tire with the softest compounds, and thus, the best adhesion.

Fact: It's sort of like kicking the tire, but with another part of your anatomy. Tread compounds only tell part of a tire's story. Tread pattern, tire shape, and tire footprint shape on the pavement provide clues to its adhesion capabilities. Don't rely on the fingernail test.

Myth: The government tests tires for traction, temperature resistance, and treadwear and assigns grades molded onto the sidewall.

Fact: Uniform Tire Quality Grading is a federal law that requires tire manufacturers to grade their own tires for treadwear, traction, and temperature resistance. Tire manufacturers, not the government, test tires and assign their own grades. Unfortunately, the government has not prescribed a formula for converting the manufacturer test results into universal grades; therefore, the numbers are not objective. According to the Federal Trade Commission, treadwear grades are for comparison purposes only and are not intended to be converted into anticipated or promised tire mileage.

Myth: An undulation on a tire sidewall is a weak spot that could lead to tire failure.

Fact: An undulation is created where materials overlap each other in the tire carcass, and it actually is the strongest part of the tire. Still, motorists perceive a "wave" on the sidewall as a defect. Goodyear's new ultratensile steel reinforcement eliminates this material splice and overlap. Ultratensile steel should reduce sidewall undulation in polyester-reinforced tires.

Myth: Before you buy a car, kick the tires.

Fact: It might not tell you much about the vehicle or tires, but it could tell you whether your shoe padding is adequate.