Functions of Wheel Alignment

Wheel alignment is an adjustment an auto shop can make on your vehicle to ensure the tires are calibrated to 'point' straight ahead. Proper wheel alignment makes a vehicle steer easily and allows tires to wear evenly. When wheels are not aligned various problems result.
Tires can be nudged out of alignment by accidentally hitting them against objects such as curbs and parking blocks, or by catching a center cement divider while making a miscalculated turn. Once a tire is knocked out of alignment, its orientation on the vehicle is slightly off-center. The degree of misalignment is not obvious to the human eye, but the effects will be noticeable.
 There are telltale signs of a vehicle in need of wheel alignment. The tire that is pointing off-center will pull the vehicle in the direction it is oriented. For example, if the right front tire is nudged slightly inward (left), the steering wheel will pull left while driving on a flat, even surface. The driver will have to maintain a right-pull on the steering wheel to keep the vehicle headed straight even when driving on a flat, straight road. This is not only annoying, but the tire that is out of alignment will also wear prematurely and unevenly because of the constant drag placed on its tread. The drag can also impact gasoline mileage.
Uneven tread wear is a sign that the car was driven quite a while with improper wheel alignment. Often, the inner tire tread will wear down smooth while there is still plenty of outer tread left, or visa-versa. The result is that tires have to be replaced sooner rather than later. If tread wear is "cupped," the vehicle was driven with the tires out of balance as well. 
Wheel alignment normally takes less than one hour. The vehicle is placed on a platform, which allows the wheels to spin while a computer calculates orientation. The computer compares this to a database of manufacturer specifications for the year, make and model of the car. If wheel alignment is off, an adjustment is made and the vehicle is tested again. Balancing can be done at the same time, if required.
The price of a wheel alignment commonly includes rotating the tires, which also helps tires wear evenly. Prices on wheel alignment vary, but you can shop around by calling for quotes. Four-wheel drive vehicles might require all four tires to be aligned, though often only the front tires need it. If your vehicle is four-wheel drive with oversized tires and a lift kit, be sure to mention this to the shop when you ask for a quote. Not all shops can accommodate vehicles with lift kits and oversized tires. You'll also want to ask if they will be aligning all four wheels or just the front tires.