For 1990-2009 cars

The toe is a measurement of how much the front of the wheels angle in or out from a straight-ahead position. When the wheels angle inward, the toe is positive (+). When the wheels angle outward, the toe is negative (-). The actual amount of the toe is normally only a fraction of a degree. The purpose of the toe is to ensure that the wheels roll parallel.

The toe also serves to offset the small deflections of the wheel support system, which occurs when the vehicle is rolling forward. When the wheels are set to toe in or out slightly when the vehicle is standing still, the tires tend to roll parallel on the road when the vehicle is moving.