Cups or dips in the tread: WORN PARTS
Cupping (also called dipping or scalloping) is more common on the front tyres, though your rear tyres can cup as well. It may be a sign that your wheels are out of balance, or that your car's suspension or steering system parts are worn out.
Sawtooth edges: MISALIGNMENT
Do the edges of the tread have a sawtooth or feathered appearance? This is caused by erratic scrubbing against the road. The solution is toe-in or toe-out alignment correction. Proper tread depth is essential for proper tyre performance. If you notice a loss or change in wet traction, you may not have enough tread left on your tyres. Once the tread depth reaches 1/16th of an inch, the tyre must be replaced.
Wear in centre: OVER-INFLATION
When a tyre is over-inflated, the centre of the tread bears most of the load and wears out faster than the outside edges. Uneven wear reduces the useful life of a tyre. Check your tyres regularly for proper inflation. Abnormal tyre wear may also be due to misalignment or mechanical problems.
Wear on both edges: UNDER-INFLATION
If your tyre looks like this, it may be under-inflated. Under-inflation reduces tread life through increased tread wear on the outside edges (or shoulders) of the tyre. It also generates excessive heat, which reduces tyre durability. Finally, it affects fuel economy through increased rolling resistance (soft tyres makes your vehicle work harder). Abnormal tyre wear may also be due to misalignment or mechanical problems.
