The toe is a measurement of how much the front of the wheels are turned in or out from a straight-ahead position. When the wheels are turned in, the toe is positive (+). When the wheels are turned out, the toe is negative (-). The actual amount of 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 that 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, the wheels tend to roll parallel on the road when the vehicle is moving. The toe affects tire wear.