In order to determine the tire positions or wheel positions automatically while the vehicle is in operation, the attenuation along a transmission path from the tire to a fixed position on the vehicle is measured and compared with stored values. Systems of this kind are error prone when other vehicles using similar systems are located in the receiving range. In order to increase the reliability of such a system it is useful to determine the attenuation along the transmission paths between the wheel units and compare it with known values. Toward that end, the novel wheel unit enables data to be provided by way of which the attenuation of the transmission path from one wheel unit to another wheel unit can be determined.