Patent ID: 7551992

Claim:
A method for detecting decompression of tires based on rotational speeds of wheels mounted on a vehicle, comprising the steps of: detecting a rotational speed of each of said wheels; determining a ground speed of said vehicle; calculating (1) speed information obtained from an average wheel speed of a front left wheel and a rear left wheel and (2) speed information obtained from an average speed of a front right wheel and a rear right wheel, from the rotational speeds of said wheels; memorizing the rotational speed of each of the wheels and the speed informations; calculating (1) a judgment value for the left side wheels by comparing the speed information obtained from the average wheel speed of the front left wheel and the rear left wheel with the ground speed of the vehicle and (2) a judgment value for the right side wheels by comparing the speed information obtained from the average wheel speed of the front right wheel and the rear right wheel with the ground speed of the vehicle; comparing the judgment value for the left side wheels with a basis value for the left side wheels obtained by comparing a speed information obtained from an average speed of the front left wheel and the rear left wheel with the ground speed of said vehicle at prescribed inner pressure to obtain a comparison value for the left side wheels; comparing the judgment value for the right side wheels with a basis value for the right side wheels obtained by comparing a speed information obtained from an average speed of the front right wheel and the rear right wheel with the ground speed of said vehicle at prescribed inner pressure to obtain a comparison value for the right side wheels; and judging decompression of tires by comparing the comparison values with a fixed threshold.