Balance and Alignment
Vehicles that are misaligned will wear the tires out much quicker than a car that is properly aligned. An alignment is nothing more than readjusting the position or angle of the wheels relative to the frame of the vehicle. Although the process is pretty straightforward it requires special equipment and should be performed only by a specialist.
Tires that are not properly balanced can cause uneven tread wear and can cause other components on the vehicle, such as the suspension, shocks, etc. to wear out prematurely. Unbalanced tires can also cause a rough ride, if you suspect that your tires need to be rebalanced, take it to a shop as soon as possible to be evaluated and balanced if necessary.
Checking the Tread
There are several ways to determine if you have a sufficient amount of tread on your tires or not.
1. Tread Wear Indicators:
Tire manufacturers build tread wear indicator bars into the tread of their tires. When the tread has been worn down so that it is level with those tread wear indicator bars, It's to let you know that it is time to replace your tires. In the picture below you can see where the tread wear indicator bars are in the tread.
2. The Abe Lincoln Test
This test is decidedly low tech but effective. Here's how:
Rotating Your Tires
Consult your owner's manual for recommendations on how to rotate the tires on your vehicle and for how often they should be rotated. Rotating the tires helps the tires wear evenly thereby maximizing the life of the tire.