Uneven tread wear - This can include more wear on one tread edge than the other, a rippled pattern of high and low wear, or exposed steel wire. Uneven wear can be caused by problems such as underinflation, vehicle misalignment and improper balancing.
Troublemakers - Check for small stones, pieces of glass, bits of metal and other foreign objects that might be wedged into the tread and carefully remove them. They can cause serious problems if they are pushed farther into your tire as you drive.
Damaged areas - Cracks, cuts, splits, punctures, holes and bulges in the tread or on the sidewalls of the tire can indicate serious problems, and the tire may need to be replaced
Valve caps - Those little caps on your tire's valve stem keep moisture and dirt out, so make sure they are on all your tires. Also, when you have a tire replaced, have a new valve stem assembly installed at the same time