Patent ID: 6865456

Claim:
An underinflation detector for a four-wheeled vehicle comprising: a rotational speed sensor to detect rotational speeds of two front wheels and two rear wheels of the vehicle; and a controller to determine that inflation pressure of a tire of any of the wheels has decreased, if a parameter calculated from outputs of the rotational speed sensor exceeds a threshold, wherein a first value of the parameter is calculated using a disparity between a front-wheel rotational speed difference and a rear-wheel rotational speed difference; and wherein correction is made to the first value of the parameter to obtain a second value of the parameter to be compared with the threshold by canceling a deviation of one of the front-wheel rotational speed difference and the rear-wheel rotational speed difference caused by a steering operation which a driver performs so as to cancel the other of the front-wheel rotational speed difference and the rear-wheel rotational speed difference arising due to underinflation of the tire.