Tire Wear Abnormalities and diagnostics

 

Tire wear patterns can tell you a lot about your car and the way it is driven. Learn to look at your tires whenever you walk up to your car to use it. This doesn't mean you have to look at all of them, but notice the ones on the side you approach. If they bulge out more than usual, check their pressures. You can find the right tire pressures written on the door inner jamb or on the tire itself. The tire pressures should be checked when cold.

 

HOW TO READ TIRE WEAR

The way your tires wear is a good indicator of other parts of your car. Abnormal wear patterns are often caused by the need for simple tire maintenance, or for front end alignment. Tires should be inspected at every opportunity; once a week isn't too often. Learning to read the early warning signs of trouble can prevent wear that shortens tire life or indicates the need for having other parts of the car serviced. Tires should be inspected 3 ways. First, visually examine all 4 tires; second, feel the tread by hand to detect wear such as feathering and third, check all 4 tires with a pocket type pressure gauge.

over inflation

Over Inflation

Excessive wear at the center of the tread indicates that the air pressure in the tire is consistently too high. The tire is riding on the center of the tread and wearing it prematurely. Many times, the "eyeball" method of inflation (pumping the tires up until there is no bulge at the bottom) is at fault; tire inflation pressure should always be checked with a reliable tire gauge. Occasionally, this wear pattern can result from outrageously wide tires on narrow rims. The cure for this is to replace either the tires or the wheels.

under inflation

Under Inflation

This type of wear usually results from consistent under inflation. When a tire is under inflated, there is too much contact with the road by the outer treads, which wear prematurely. Tire pressure should be checked with a reliable pressure gauge. When this type of wear occurs, and the tire pressure is known to be consistently correct, a bent or worn steering component or the need for wheel alignment could be indicated. Bent steering or idler arms cause incorrect toe-in and abnormal handling characteristics on turns.

If the tire has a smoothly rounded tread profile, the driver must take the blame. Fast driving around corners is the cause of the problem.

feathering

Feathering

Feathering is a condition when the edge of each tread rib develops a slightly rounded edge on one side and a sharp edge on the other. By running your hand over the tire, you can usually feel the sharper edges before you'll be able to see them. The most common cause of feathering is incorrect toe-in setting, which can be cured by having It set correctly. Occasionally toe-in will be set correctly and this wear pattern still occurs. This is usually due to deteriorated bushings in the front suspension, causing the wheel alignment to shift as the car moves down the road.

A severe toe problem can wear rubber rapidly from both tires or even from all four. Tires that squeal easily on turns, or make a loud hissing noise as they roll, may also be signaling toe troubles. (The hissing is noise reflected from parked cars that you drive by.) Car handling may or may not be affected.

one side wear

One Side Wear

When an inner or outer rib wears faster than than the rest of the tire, the need for wheel alignment is indicated. There is excessive camber in the front suspension, causing the wheel to lean too much to the inside or outside and putting too much load on one side of the tire. The car may simply need the wheels aligned, but misalignment could be due to sagging springs, worn ball joints, or worn control arm bushings. Because load has a great affect on alignment, be sure the car is loaded the way it's normally driven when you have the wheels aligned; this is particularly important with independent rear suspension cars.

(High cambered Roads and high speed turns can also cause this condition)

cupping

Cupping

Cups or scalloped dips appearing around the edge of the tread on one side or the other, almost always indicate worn (sometimes bent) suspension parts. Adjustment of wheel alignment alone will seldom cure the problem. Any worn component that connects the wheel to the car (ball joint, wheel bearing, shock absorber, springs, bushings, etc.) can cause this condition. Worn components should be replaced with new ones. The worn tire should be balanced and possibly moved to a different location on the car. Occasionally, wheels that are out of balance will wear like this, but wheel imbalance usually shows up as bald spots between the outside edges and center of the tread.

Once an uneven wear pattern is set, correcting the cause alone will not improve the pattern. Tire rotation is called for. When placed on a rear wheel, a front tire that has become cupped will partially true its tread.

tire rib

Second-rib Wear

Second-rib wear is normally found only in radial tires, and appears where the steel belts end in relation to the tread. Normally, it can be kept to a minimum by paying careful attention to tire pressure and frequently rotating the tires. Some car and tire manufacturers consider a slight amount of wear at the second rib of a radial tire normal, but that excessive amounts of wear indicate that the tires are too wide for the wheels. Be careful when having oversize tires installed on narrow wheels.

Tread blocks with a saw-toothed wear pattern indicate too much or too hard use of brakes. The problem is called heel-and- toe wear. A certain amount of such wear is normal. Rear tires show it less than front tires because they receive a driving force from the engine that wears off the opposite ends of their tread blocks. But only braking forces act on the front wheels of conventional, rear-wheel-drive cars. The remedy is to change driving habits and to abnormal wear by rotation if the problem becomes serious enough to produce tire noises.

 

A vibration or a whining sound that is especially noticeable on a smooth road may signal tread abnormalities. Unless it is a wheel tramp that comes once with every revolution of the wheels, it may be tough to tell from differential gear noises.

To tell tire, noise from gear or exhaust noise, find a smooth stretch of highway. Drive at various speeds and note the effect of accelerating and decelerating. When it is safe to do so, brake lightly. Axle and exhaust noises change in intensity under these conditions. Tire noises, though, usually stay the same throughout.

If tires seem to be the cause, balance all the wheels temporarily, inflate them to 45 psi, and drive the road again at the same speeds. If the noise is changed or eliminated, deflate one tire at a time to the proper pressure, repeating the road test with each deflation. When the noise returns to what it was, the last tire deflated is probably the offender.

Wheel tramp (also called tire thump) usually occurs between 20 and 40 mph. The bad tire is easy to locate with the tire- at-a-time deflation method. The only cure for a thumper is replacement.

Tire roughness from two or more thumping tires, or one tire with more than one thump-spot, most often shows up at speeds between 40 and 70 mph. Tire roughness feels like a low-frequency rumble or vibration. It may be felt in the seat or steering wheel, or both. Front tire thumps are most noticeable in the steering wheel, while rear tire thumps usually show up as seat vibrations. To find the trouble maker(s), you may have to replace the tires one at a time with the spare. For this, all tires should be at normal pressure.

An out-of-balance driveshaft can feel like thumping tires. To tell one from the other, block up the rear axle, remove the wheels, and accelerate the engine with the transmission in gear. Hold the accelerator pedal at the speed where the vibration was most pronounced. If you feel no vibration, the front or rear tires are the cause. If the vibration is still there, the driveshaft is the likely cause.

 



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