Tyre tread depth during vehicle travel with a ratio of wear between two axles

A process for determining an actual reference profile depth on a tire on a vehicle axle, comprises determining the wear on the profile of a tire on a second axle, using the reference profile depth, and then determining the actual reference profile depth from the wear and the wear relationship between the two tires. A process for determining an actual reference profile depth on a tire on a vehicle axle, comprises determining the wear on the profile of a tire on a second axle, using the reference profile depth, and then determining the actual reference profile depth from the wear and the wear relationship between the two tires. The reference rotational frequency of the reference tire is measured, along with the rotational frequency of the tire on the second axle. A quotient is then formed from the reference rotational frequency and the rotational frequency, which is then multiplied by the reference profile depth to determine the actual depth. The arrangement used to determine the profile depth includes a sensor (47), a data storage unit (49), a computer (48) and a display (55).