When the tire reaches a limit of wear level, tire wear indicators generate an acoustic signal by knocking the ground. Magnetic, optical and mechanical versions exist.A detector made of a microphone located under the vehicle and a processing central unit switches on a warning included in the dashboard.In a more sophisticated version, the detector recognizes the incriminated wheel using the phase of the acoustic signal and the information from the ABS™. Application to the detection of the decay of a tire, or any other type of wear surface such as pad, or similar, and to the detection of the presence of snow chains or spikes.