Vehicle wheel alignment adjustment method

Abstract

A wheel angle of a wheel is adjusted in accordance with the characteristics of tire of the wheel such that a steering characteristics of the vehicle is substantially neutral steer. The wheel angle of a reference wheel of the vehicle (for example, a rear wheel) is adjusted. Next, the reference wheel and a non-reference wheel (for example, a front wheel) are rotated on the tire driving surface of an endless track on which are formed a plurality of plate-like protrusions of a predetermined height. The longitudinal and lateral forces generated in the tire are then measured. On the basis of the wave forms of the rate of change measured in the longitudinal force, a predetermined period is determined from the time when the tire is deformed as the wheel passes over the upward step of the protrusion until the tire is deformed as the wheel passes over the downward step of the protrusion, and data of the lateral force measured within the predetermined period is extracted. The wave forms of the lateral forces of both wheels indicated by the extracted data are superposed, and the direction in which the toe angle of the non-reference wheel should be adjusted is calculated on the difference in the wave forms.