Caster setting wheel alignment is the angle that identifies the forward or backward slope of a line that is drawn through the upper and lower steering pivot points. It does not affect tire wear, but the caster does influence the directional control of the steering. Caster angle settings allow manufacturers to balance steering effort, high-speed stability, and front-end cornering effectiveness.

Positive Caster -  If the line slopes towards the rear of the vehicle, then you have a positive caster. The downside to a positive caster is if the vehicle does not have power steering. In this case, the steering effort will be increased. A positive caster is primarily beneficial to the vehicle as it increases the lean of the tire when the vehicle is cornering while returning it to an upright position when driving straight ahead.