In vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing (i.e., the angle of the vector sum of wheel forward velocity and lateral velocity ). For a free-rolling wheel this slip angle results in a force parallel to the axle and the component of the force perpendicular to the wheel's direction of travel is the cornering force. This cornering force increases approximately linearly for the first few degrees of slip angle, then increases non-linearly to a maximum before beginning to decrease.