Knowing how to read your automobile’s tire wear is important to your vehicle’s performance and your safety. Premature or abnormal tire wear is commonly due to the lack of basic tire maintenance and upkeep, incorrect tire alignment, or worn suspension components.
The Quarter Test
One quick way to check the tread on your tires is to use a quarter (not a penny, as was used for many years).
The tread on your tires should be greater than 4/32”. The old penny test only lets you know if you have 2/32” of remaining tread, which isn’t good enough if you plan on driving in rain or snow (basically if you live anywhere - on any continent). The quarter test is a better indicator:
Place an upside down quarter between the tread ribs on your tire.
If the top of Washington’s head disappears between the ribs, your tread is still above 4/32 of an inch -- which is good.
If you can see Washington’s entire head, it’s about time to replace that tire.
Remember, the quarter test is just an indicator. If you think your tires may be close to needing replacement, have them checked by a licensed mechanic.
Keep reading to learn how to read and decipher tire wear patterns.
If your car’s or truck’s tires are excessively worn down in the center, their tire pressure is consistently too high. The high level of pressure causes the center of the tire to be the primary patch of contact to the road, resulting in premature wear. Tire pressure should be checked regularly with a tire pressure gauge.
Consistently under inflated tires also suffer from uneven and premature tire wear, but from too much contact between the outer tread of the tire and the road. if you notice uneven tire wear and your tire pressure is consistently correct, you might want to look for other causes - like alignment issues. Similar uneven tire wear patterns can result both from under-inflated tires as well as from damaged steering components.
Feathering occurs when the edge of each tread rib becomes slightly rounded on one side and edged on the other. Two possible causes for feathering are too much toe-in (which can be fixed with an alignment) or worn suspension components (which result in the tire not tracking straight down the road like it should).
Visible wear on the inner or outer tread ribs of your vehicle’s wheels could be the result of too much camber. Camber, which can be either positive or negative, is the angle at which the wheel and tire stand relative to the road and will cause the tire to tilt too far to one side or the other, thereby applying too much pressure to the shoulder of the tire.
Cupping, also called scalloping, occurs around edges of the tread from the tire bouncing sideways during its phases of rotation. Worn suspension components (e.g. shocks, ball joints, springs, control arms) can cause this condition, as well as can a misalignment or incorrect tire balancing. Worn components should be replaced immediately.
Second-rib wear, a condition commonly found only with radial tires, appears where the steel belts within the tire end in coordination with the tire’s tread. You can help prevent this type of wear by paying close attention to tire pressure and getting frequent tire rotations. While such tire wear is considered normal for certain makes and models of tire, excessive amounts are a good indication that the wheels aren’t wide enough for the tires.
Good practice is to check your tires twice a month for any abnormal wear, and to keep up with the correct recommended tire pressure levels.
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