Tread Wear Patterns – and why:

The most important reason to worry about tread wear is safety. As your tires wear down, their ability to grip the road decreases. Your car may respond poorly in rain and snow. With good treads, your car will grip the road better.

UNDER-INFLATION: Both edges worn. Remedy: Add more air; check for leaks.
OVER-INFLATION: Center treads worn. Remedy: Let air out to manufacturer’s specifications.

ONE-SIDED WEAR: Poor alignment. Remedy: Have wheels aligned.

WARNING:

Under-inflated tires wear out faster, create excessive heat, increase fuel consumption, and make your car harder to handle.
Over-inflated tires can “blow out” more easily, wear out faster, and make the car unstable and unsafe to handle.

A penny can buy you peace of mind when it comes to your tires and safety.

Most tires have tread-wear indicators built into them. These bars of hard rubber are normally invisible but appear across treads that have been worn down to 1/16th of an inch of the surface of the tire (the legal limit in most states). If these indicators appear in two or three different places, less than 120 degrees apart on the circumference of the tire, replace the tire.

OLD TIMERS TIP: If your tires don’t show these indicators and you think that they may be worn below legal tolerances, place a Lincoln penny head-down in the groove between the treads.
If you can see the top of Lincoln’s head, your tire probably needs to be replaced and it’s time to have a professional check them.