Wheel alignment and Wheel Balancing are two totally different things, but many people often get them confused. In a nutshell, wheel alignment consists of adjusting the angles of the wheels so that they are perpendicular to the ground and parallel to each other.
The purpose of these adjustments is maximum tire life and a vehicle that tracks straight and true when driving along a straight and level road. Wheel Balancing, on the other hand allows the tires and wheels to spin without causing any vibrations.
This is accomplished by checking for any heavy spots on the wheel-tire combination and compensating for it by placing a measured lead weight on the opposite site of the wheel from where the heavy spot is.
Tofind out if you need an alignment, first check each tire and look for uneven wearpatterns. The problem with this method, however, is that if you can see a wear patternlike the ones listed below, it may be too late to save that tire. This is why it is a goodidea to have your alignment checked periodically. At each tire, take a coin and insert it in the tread at the inside, center and outside.
If the tread is smooth in one direction, but jagged in the other you have what is called a "saw-tooth" wear pattern which is caused by a toe-in problem. Have the alignment checked as soon as possible as this condition causes rapid tire wear. The first two conditions do not call for a wheel alignment but the second two do. If these wear patterns are pronounced, you should replace the tires or move them to the rear before aligning the car. Ask your alignment specialist to be sure.
Another indication of an out-of-alignment condition is a car that continuously drifts or pulls to one side of the road when you let go of the wheel. A car that is hard to keep in a straight line without constant steering corrections is also a candidate. These conditions may or may not also contribute to premature tire wear.
A wheel alignment cannot be done on a car with loose or worn front end parts. The technician will first check for worn parts and inform you of any problems before beginning the alignment.
The best type of wheel alignment is a four wheel alignment. Many cars today have adjustable rear alignment settings, but even for cars without adjustments in the rear, a four wheel alignment will allow the technician to identify any rear tracking problems and compensate for them with adjustments to the front.
After the wheel alignment is finished, you should drive the car on a straight and level road and check that the car goes straight and that the steering wheel is in the proper position with the spokes level. If you notice a problem,take the car back and have the technician drive it and fine-tune the alignment settings.
Out-of-balance tires will cause a car to vibrate at certain speeds, usually between 50 and 70 mph. A tire is out of balance when one section of the tire is heavier than the others. One ounce of imbalance on a front tire is enough to cause a noticeable vibration in the steering wheel at about 60mph. To balance a wheel, the technician will mount it on a balancing machine which spins the wheel to locate the heavier part. He will then compensate for the heavy part by attaching a lead weight on the opposite side. Many people are pleasantly surprised at how smooth their car drives after balancing all four wheels.
Most high quality tires will hold their balance fairly well and go out of balance very gradually. If you notice a vibration that wasn't there the day before, it is possible that one of the lead balancing weights fell off. If you feel the vibration mostly in the steering wheel, the problem is most likely in a front wheel. If the vibration is mostly in the seat, the problem is probably in the rear.
For those of you who are very sensitive about vibrations and your shop can't seem to get that last bit of vibration out, check to see if you have locking wheel lugs. Some locking lugs are as much as 1.5 ounces heavier than the other lug nuts which translates to about 1/2 ounce at the wheel rim. Try putting a 1/2 ounce weight opposite the locking lug and see if it helps.