Toe (automotive)

In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e. both wheels point to the left or right, in parallel (roughly). Negative toe, or toe out, is the front of the wheel pointing away from the centreline of the vehicle. Positive toe, or toe in, is the front of the wheel pointing towards the centreline of the vehicle. Historically, and still commonly in the United States, toe is specified as the perpendicular (to the vehicle's centerline) distance between the wheel's centerline and an imaginary line passing through the center of rotation, parallel to the vehicle's centerline, measured at axle-height, at the outside edge of the wheel. Since the toe value in that case depends on the tire diameter, the linear dimension toe specification for a particular vehicle may be specified for specific tire sizes, or tire size ranges; while a toe angle is independent of tire size.