Mustang Club of Maryland

A guide to tire inspection and diagnosis

Fortunately, tires seldom fail without warning and this warning often comes in the form of abnormal wear. In fact, tires are excellent at telling you whether or not they are wearing normally and, if not, what is to blame.

Some key symptoms to look for and suggest some easy corrections:

Upon examining your tires, you'll find the two primary parts are the tread and the sidewall. The tread is reinforced by multiple steel belts that provide additional protection against puncture. The sidewall is not.
Because of this difference, you will want to begin any tire inspection with a careful examination of the sidewall. Look for any cuts, bubbling, or cracking. If you find any of these, take your tires to a local tire retailer immediately for a professional inspection. Because of the delicate nature of the sidewall, it is
advisable to install your spare tire before driving.

In addition to the sidewall, you'll want to give the tread a thorough inspection. Start your review by checking the depth of the tread. This will give you an idea of how many miles you've got left before some new rubber is required.

Every tire is equipped with several wear indicators that run across the tread in the grooves between the tread ribs. Once these wear indicators are flush with the ribs, it is time to replace the tire. Another method for checking tread depth is to insert a penny in one of the grooves with Lincoln's head upside down and facing you. If you can see the top of Lincoln's head, it is time to replace your tire.

During your examination you will also want to check for any abnormal wear. If the tread depth is uneven, note where the wear is occurring. You should be able to determine its source and, if it's not too late, correct it before you eat through the rest of your tire's useful life. There are four common causes of premature tire wear: improper inflation, misalignment, lack of rotation and front end wear.

Proper inflation is essential for normal wear on your tires. If your tires are under-inflated, the sidewall will sag causing excessive wear on the outside areas of the tread. Under-inflation also results in excessive heat, which accelerates wear and may cause a blow out. Tires that are over-inflated will show wear down the middle, with the outside edges remaining in relatively good condition. This, too, is a bad thing, causing accelerated wear that will decrease your tire's life. Try dropping the pressure down a few pounds to even out the wear.

The key here is checking your tire pressure at least twice a month. Manufacturer recommended tire pressures are usually printed on a label that is placed in the driver's-side door jam. When filling your tires, note the average outside temperature. Hotter temperatures will expand the air in your tires raising the pressure by a few pounds and, at the same time, cooler temperatures will see a reduction in pressure. This is another good reason to check your tire pressure regularly.

Wheels that are out of alignment may also cause unusual and excessive tire wear. Tires that are heavily worn on one side or the other are riding at an angle and not flat on the ground. A side effect of this condition is decreased traction due to reduced contact with the road. See your local tire retailer to determine if a wheel alignment will resolve the condition.

A third aspect of any good tire inspection should include a comparison between the tread depths on the front and the rear tires. The rubber on the front of your car will diminish much faster than that on the rear due to increased friction when turning. The difference in wear between front and rear is amplified on front-wheel-drive cars. The simple solution for this occurrence is regular tire rotation. Front tires will always wear faster, but by swapping the front and rear tread every 6,000 to 8,000 miles all tires will wear evenly in the end.

The final test before you pass your tire inspection test is to make sure the tread is wearing evenly around the circumference of the tire. Poorly balanced wheels or worn front-end components may cause the tire to bounce on the road causing a condition known as cupping. This condition, also know as scalloping, dipping and feathering, causes areas of the tread to wear more rapidly making the tire out of round. As a result, the normally smooth tread suddenly has peaks and tips every few inches all the way around. And unless you have about $50,000 in highly specialized equipment, the only way to correct this condition is to consult a professional repair facility for a thorough diagnosis.

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