Toe is the measurement of how much the fronts 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 toe is to ensure that the wheels roll parallel. Toe also serves to offset the small deflections of the wheel support system which occur when the vehicle is rolling forward. Incorrect toe-in or incorrect toe-out will cause tire wear and less than optimum economy. As the suspension and steering systems wear with extensive vehicle mileage, additional toe will be needed in order to compensate. Correct the toe dimension last.