Patent ID: 7305288

Claim:
A method for detecting decrease in tire air-pressure on the basis of wheel rotational information obtained from tires attached to a four-wheeled vehicle, comprising the steps of: obtaining wheel rotational information by subjecting rotational information obtained from the respective tires to an initial correction on the basis of the rotational information, to eliminate the influence of initial differences in the tires; storing the wheel rotational information; and judging decrease in air-pressure of a tire to obtain a judgment of decrease in tire air-pressure, wherein the step of judging decrease in air-pressure includes (1) adjusting a sensitivity of judgment by multiplying a specified sensitivity coefficient to the wheel rotational information of (a) the respective wheels of a front axis or (b) the respective wheels of a rear axis of the vehicle and (2) judging a running condition of the vehicle, and wherein when it is determined that the vehicle is performing straight-ahead running, the judgment of decrease in tire air-pressure is performed only on the basis of said wheel rotational information by eliminating data during turning movements when performing said straight-ahead running.