Generally speaking, the most common causes of incorrect wheel alignment is worn or lose suspension components, impact which can alter the alignment, a change in suspension height caused by sagging springs or excessive load carrying.
Deterioration of wheel alignment can occur gradually. The effect of this deterioration may range from a barely noticeable vibration in the steering to a violent shudder of the car and severe pulling towards one side of the road.
There are two types of wheel alignment: 2 wheel and 4 wheel. 2-wheel alignment involves aligning the front wheels only and is satisfactory for older model vehicles with a solid rear axle. Pedders recommend that all-recent model vehicles i.e. those with out a solid rear axle require a 4-wheel alignment. This involves aligning all four wheels together. Particularly for front wheel drive and those with independent rear suspension. Failure to align all four wheels may compromise safety and handling characteristics.