Patent ID: 8350688
Filing Date: 2013-01-08
Classification: B60C

Abstract:
1. A method of indirect tire pressure monitoring for indicating when a pneumatic tire on a wheel at one end of a motor vehicle axle is underpressurized relative to a pneumatic tire on a wheel at an opposite end of the axle while the vehicle is being driven on a road surface, the method comprising: repeatedly calculating difference between a current measurement of effective radius of each tire relative to a reference value for effective radius of the same tire; processing the calculated differences for each tire to calculate a value of a first-order derivative of effective radius of the same tire and comparing the calculated value of the first-order derivative of effective radius of one tire to the calculated value of the first-order derivative of effective radius of the other tire; and when the comparison of the calculated values of the first-order derivatives of the respective tires discloses that the value of one of the first-order derivatives differs from that of the other of the first-order derivatives by more than a defined amount, using that disclosure to determine if an alert for indicating that one tire is too underpressurized relative to the other should be issued.