Caster

Caster is the tilting of the front steering axis (at the top) either forward or backward from the vertical. A backward tilt is positive (+) and a forward tilt is negative (-). Caster influences directional control of the steering but does not affect tire wear and is adjustable only at the front tires and wheels.

Caster is affected by vehicle height. Therefore, it is important to keep the body at its designated trim height. Overloading of the vehicle, or a weak or sagging rear spring will affect caster. When the rear of the vehicle is lower than its designated trim height, the front suspension moves to a more positive caster. If the rear of the vehicle is higher than its designated trim height, the front suspension moves to a less positive caster.