Toe is a measurement of how much the front or rear of the wheels are turned in or out from a straight-ahead position. When the wheels are turned in, toe is positive. When the wheels are turned out, toe is negative. The actual amount of toe is normally only a fraction of a degree.

Toe functions in order to ensure that the wheels roll parallel. Toe also offsets the small deflections of the wheel support system that occur when the vehicle is rolling forward. The wheels are set to toe-in slightly when the vehicle is standing still. Wheels that have the proper toe will tend to roll parallel on the road when the vehicle is moving.

An incorrect toe condition will cause abnormal tire wear and decreased fuel economy.

Thrust angle is defined as the path the rear wheels will take. If the rear wheel path is the same as the path of the vehicle, the thrust angle is zero. Ideally, the thrust angle should be aligned perfectly with the centerline of the vehicle.