Method for determining the depth of tread of a vehicle tire with a tire module arranged on the inner side of the tire

A method for determining the depth of tread in a tread strip of a vehicle tire having a tire module arranged on the inner side of the tire lying substantially opposite the tread strip, the tire module including an acceleration sensor for measuring acceleration values (a, a0, a1, a2) in the radial direction, the method comprising the steps of:

• a) measuring acceleration signals emitted from said tire module;
• b) determining a minimum acceleration value (a2) during rotation of the vehicle tire and at a constant traveling speed (V) when, at the time point of the measuring of the acceleration signals, the tread strip with the tire module is disposed in the region of the ground contact area of the vehicle tire;
• c) determining the maximum internal radius (r2) of the inner side of the tire in the center of the ground contact area of the vehicle tire from the quotient of the traveling speed (V) squared and the minimum acceleration value (a2) with the maximum internal radius (r2) defining the curvature of the inner side of the tire in the circumferential direction of the ground contact area and being substantially dependent on the thickness of the rubber package between the tire belt and the roadway;
• d) determining the depth of tread of the vehicle tire with signal processing with the maximum internal radius (r1) changing significantly as the depth of tread decreases and the determination of the depth of tread being based on the fact that the depth of tread is coupled with the maximum internal radius (r1) via a direct mathematical function (Equation II);
• and,
• e) then doing at least one of the following:
• transmitting the determined depth of tread to a receiving unit in the vehicle and indicating the depth of tread by an indicating device.