A very important wheel alignment angle you should know something about is the camber. Camber refers to the tilt of the wheels as seen from the front or rear. Camber is the inward (negative) or outward (positive) tilt of the wheels. It is always measured in degrees.
As with toe, zero camber (perfectly perpendicular to the road) is the ideal alignment setting too. But like toe, camber changes as the vehicle is being loaded and every time the vehicle encounters a bump or dip in the road. The up and down movements of the suspension changes the geometry of the control arms and struts, which then causes the camber to change. So many static camber alignment specifications may permit up to a degree of more of positive or negative camber depending on the design of the suspension. As a standard, camber settings should usually be within half a degree side-to-side.
If camber is out of specification, a tire will wear unevenly on one shoulder and the vehicle may pull toward the side with the most camber. Camber usually only affects one wheel, so if only one tire shows unusual shoulder wear it is usually a sign of camber misalignment.
Note that camber applies to both front and rear wheels, though only cars with independent rear suspensions typically have rear camber alignment specs. Most rear-wheel drive cars and trucks with solid axles do not have rear camber specifications because there’s no way to change it (even at these, a bent rear axle can create a camber problem!).
Excessive camber can be caused by a bent spindle, mislocated strut tower, bent strut, worn or collapsed control arm bushing, bent control arm or a weak or broken spring. If any of these parts are replaced, camber should be checked and adjusted as needed after the parts have been installed. And of cars that do not have camber adjustments on the struts or control arms, or provide only a limited amount of adjustment, there are aftermarket camber adjustment aids that can assist.