Toe is a measurement of how much the front of the wheels are turned in or out from the geometric centerline. When the wheels are turned in (toe-in) (2), toe is positive. (+). When the wheels are turned out (toe-out) (1), toe is negative. (-). The actual amount of toe is normally only a fraction of a degree. The purpose of toe is to ensure that the wheels roll parallel.

Toe also serves to offset the small deflections of the wheel support system which occurs when the vehicle is rolling forward. In other words, even when the wheels are set to toe in or out slightly when the vehicle is standing still, they tend to roll parallel on the road when the vehicle is moving. Toe also affects tire wear.