Method and device for operating a traction aid of a vehicle

The method involves transmitting light (11) of a wavelength on a road surface (1a) e.g. concrete road surface, below a vehicle (60). The light reflected by the road surface is detected. Information about condition of the road surface is determined based on the detected reflected light. A determination is made whether a traction aid is necessary or not by a frictional coefficient of the road surface based on the information. The traction aid is controlled when determined whether the traction aid is necessary or not by releasing a releasable axle (63) of the vehicle. An independent claim is also included for a device for controlling a traction aid of a vehicle.