System for determining pneumatic tire pressure for motor vehicle

Claim 1

A system for determining a pneumatic tire pressure of road wheels on a motor vehicle, comprising: first differential speed means for detecting a front rotational speed difference between rotational speeds of front left and right road wheels of the motor vehicle; second differential speed means for detecting a rear rotational speed difference between rotational speeds of rear left and right road wheels of the motor vehicle; running condition detecting means for detecting a running condition of the motor vehicle; reference differential speed calculating means for calculating a reference rotational speed difference between rotational speeds of the front left and right road wheels based on an output signal from said third means; first pressure reduction determining means for comparing said front rotational speed difference and said rear rotational speed difference to determine a pneumatic tire pressure reduction of said front left and right road wheels or said rear left and right road wheels; second pressure reduction determining means for comparing said front rotational speed difference or said rear rotational speed difference and said reference rotational speed difference to determine a pneumatic tire pressure reduction of one of said front left and right road wheels or said rear left and right road wheels; and final pressure reduction determining means for determining a pneumatic tire pressure reduction from output signals from said first pressure reduction determining means and said second pressure reduction determining means based on a first ratio in said first pressure reduction determining means and a second ratio in said second pressure reduction determining means.