Abstract: A tire pressure detector of an automobile, comprises a magnet having N and S poles and rotated in accordance with a pneumatic pressure in a tire, the N and S poles being rotatable in reverse, detecting means, arranged opposite to the magnet, for detecting magnetism and outputting a voltage signal changed to different magnetism level in accordance with rotation of the magnet, and determining means for comparing the voltage signal with a positive or negative threshold value and determining whether the pneumatic pressure in the tire is within a suitable range, based on a polarity of the voltage signal represented by a comparison result.

Abstract: Rear wheels are controlled based on rear-wheel slip angle (.beta.r). A desired rear-wheel steering angle (.delta.r) is expressed as .delta.r=-G(S)kr.beta.r, where G(S) is a derivative transfer function and kr is a steering coefficient. The desired rear-wheel steering angle is applied to a rear-wheel steering control system for controlling the rear wheels to the desired rear-wheel steering angle.