What is the primary purpose of caster in wheel alignment?

The primary purpose of caster in wheel alignment is to enhance steering stability. Caster refers to the angle of the steering axis when viewed from the side of the vehicle. When designed with a positive caster angle, the steering axis tilts backward toward the rear of the vehicle at the top.

This design provides a self-centering effect as the wheels want to naturally return to a straight-ahead position after a turn, enhancing stability during straight-line driving and improving the overall handling of the vehicle. This is particularly important for maintaining control, especially at higher speeds.

While caster does influence tire wear indirectly through its effect on stability and handling, its direct role focuses on maintaining steering control and stability. The other options relate to different aspects of wheel alignment or suspension settings but do not pertain directly to the primary role of caster.