Caster

Caster is the tilting of the front steering axis, either forward or backward from the vertical. A backward tilt is "positive," and a forward tilt is "negative." If one wheel has more positive caster than the other, it will cause the wheel to pull toward the center of the vehicle. This will cause the vehicle to move or lead toward the side with the least positive caster.

Caster influences directional control of the steering, but does not affect tire wear. Weak springs or overloads will affect caster.