Caster Angle 👌🚗 The caster angle is a geometric parameter in automotive engineering that refers to the angle of inclination of the steering axis from the vertical axis of a vehicle, as viewed from the side. In simpler terms, it's the angle formed by a line drawn through the upper and lower steering pivot points (typically the upper and lower ball joints or the upper strut mount and lower control arm ball joint) and a vertical line when viewed from the side of the vehicle. Positive caster angle