Proper wheel alignment optimizes vehicle handling, maximizes fuel economy, and minimizes tire wear. If the wheels are properly aligned, the driver has to exert very little force while driving on straight, level roads. Wheel alignments should be performed when the vehicle pulls to the left or right, abnormal tire wear is noticed, new tires are installed, suspension or steering parts have been replaced, after an accident, hitting a curb, or going in the ditch. Terms used to describe how a tire aligns with the road are caster, camber, and toe.
Abnormal Tire Wear. Abnormal tire wear is effected by tire inflation, wheel balance, and wheel alignment.
Caster. Caster is the steering axis angle – the forward or backward tilt from absolute vertical as viewed from the side of the vehicle. Forward tilt is negative caster while backward tilt is positive caster. Caster effects stability and control.
Camber. Camber is the inward or outward tilt of the tire from absolute vertical when viewed from the vehicle’s front. When the top of the tire leans outward, it has positive camber. When the top of the tire leans inward, it has negative camber.
Toe. When the front distance of a pair of tires is less than the back, it is defined as toe-in. When the front distance of a pair of tires is greater than the back, it is defined as toe-out.