Caster

Caster is the tilting of the uppermost point of the steering axis, either forward or backward from the vertical, when viewed from the side of the vehicle. A backward tilt (at the top) is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect tire wear. If one wheel has more positive caster than the other, it will cause that wheel to pull toward the center of the vehicle. This condition will cause the vehicle to move or lead toward the side with the least amount of positive caster.