The way tires wear is often a reliable indicator of the overall condition of a vehicle, but the problem is that some types of tire wear can have multiple causes that are often not related. So what does it mean when a tire wears in a particular manner? The cause is not always easy to pin down, and although most uneven wear on tires are easily fixed, there are some that cannot be repaired.

Uneven tire wear that is the result of the car being assembled sloppily can often not be repaired, but fortunately, these cases are relatively rare. The majority of uneven tire wear issues can be corrected, and in this article, we will look at some of the most common causes of uneven tire wear, and what you can do to fix the problem.

Uneven Tire Wear Explained - Auto Body Shop Blog

Over Inflation

Tires that are consistently over inflated tend to bulge outwards in the centre of the tread, causing the central part of the tread to wear faster than the edges. This often results from using the “eye-ball” method of tire inflation, where the tires are inflated until the bulge at the contact point with the road disappears.

Most radial tires are designed to have this bulge, so the only reliable method to inflate modern tires is to check the pressure with a reliable digital tire pressure gauge. However, premature wear of the central part of the tread can also occur on tires that that are too wide for the rims they are fitted to. There is no remedy for this other than to replace the tires and the rims with tire/rim combinations that are matched.

Under Inflation

Consistent under inflation of tires cause the central part of the tread to bulge inwards, leaving the edges of the tread to carry the full weight of the vehicle. However, if the problem is related to inflation, both edges of the tire will wear at the same rate.

Even though a tire may appear not to be under inflated when it is checked visually, steering action may be imprecise, stopping distances will increase, and the car may even “wander” across the road, and especially on road surfaces that are not perfectly flat.

In cases where one edge wears faster than the other, there is under inflation present in combination with something else, such as worn, or damaged suspension and/or steering components.

Feathering

This refers to a condition where one edge of the tread blocks develops a distinctly raised edge in relation to the other edges. The best way to check for this is to run your hand over the tread in both directions. If feathering is present, you will feel the raised edges in one direction, but not in the other.

This condition is usually caused by incorrect toe-in or toe-out settings, which mean that the front sided of the tires, are either facing inwards or outwards too much. However, if these settings are incorrect, both tires will have close to the same amount of feathering, and the remedy is a simple wheel alignment that will reset the wheels t the correct angles.

On vehicles where feathering is present on only one wheel, the cause is almost certainly worn or damaged steering and/or suspension components on the affected side. This type of damage is typically caused by colliding with potholes or other obstacles, and the remedy is a thorough inspection of the suspension on the affected side, and replacement of all damaged components.

Wear on one side of the tread

This can be caused by severe cases of misaligned wheels if the wear is equal on both sides of the vehicle, and on either the inside or outside edges of the tread. In cases where the uneven wear occurs on only one wheel, the cause is almost certain to be related to the amount by which the wheel deviates from the vertical.

This is referred to as the “camber” of the wheel, and in nine cases out of ten, the wear is on the inside edges of both tires- but not always. Possible causes include worn or damaged control arm bushings, incorrect camber settings, worn shock absorber strut mountings, worn wheel bearings, worn tie-rod ends, worn ball joints, and deformation of the body due to accident damage.

The remedy includes correction of the camber settings, and/or the replacement of all damaged and/or worn steering components. If the problem persists, have the vehicle checked by a competent body shop to check for deformation of the body shell.

Diagonal wear bands

On tires that show equidistantly-spaced diagonal bands of wear around the circumference of the tire, the problem is related to excessive free play in adjustable wheel bearings. In this condition, a part of the tread does not follow the plane of rotation of the wheel exactly. At some point in the rotation, a part of the tread moves sideways relative to the plane of the wheel’s rotation, thus causing the tire to wear diagonally in some parts.

However, the damage on such a tire is permanent, and even if the wheel bearings are replaced, the wear pattern will get progressively worse until the tire becomes completely unfit for further service.

Worn spots around the circumference of the tire

Bald or worn spots around the circumference of a tire are always a sign of worn shock absorbers. Shock absorbers have the purpose of damping out suspension movements, so if the shocks are worn, the there is nothing to prevent the wheels from bouncing up and down.

When this happens, parts of the tire are forces into the road surface when the wheel moves downwards, which causes that spot on the tread to wear faster. Once this process has started, it cannot be reversed, even if all the shock absorbers are replaced. The flat spots mean that the tire is no longer round, and because of this, some parts of tire will continue to wear at a progressively faster rate as the flat spots increase in size.

Tires with this type of wear must be replaced along with the shock absorbers, and the suspension must be checked for damaged caused by the vibration of the unevenly-worn tire(s).

Wear on the second rib

This refers to a condition where the tires wear in a narrow strip between the centre of the tire and the extreme edges of the tread, which are normally not greatly affected. This type of wear is common on tires that are too wide for their rims, and the wear always takes place where the steel reinforcing bands in radial tires end relative to the edge of the tread.

Although some tire and car manufacturers regard nominal wear in this area as normal, the extent of the wear can often be controlled by maintaining the correct tire pressure. However, if the wear is severe, or is accelerating, the only remedy is to replace the tire/rim combination with rims and tires that are more closely matched.

References:
Tire Tread Wear & Causes

This article is provided by the staff writers of AutoBodyShop.org – the largest Auto Body Shop Directory in the US with over 200.000 verified listings. At our Auto Body Shop Blog you find more interesting articles about car and road safety.

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