Device used to free a vehicle that is stuck in terrain or to reduce such risk through the use of an additional tread disposed parallel to each wheel of the vehicle. The additional tread can be an air chamber (2 or 10a and 10b) covered or not with a tire (11) or a band comprising different coupling profiles (13, 14 or 15). The tread is mounted onto an anti-sink rim comprising a conical profile (1.2) and a flange (1.1) centered in and applied against the outer side of the wheel disc by special bolts (6) inserted in respective openings in the flange and rim. The diameter of the system is smaller than that of the wheel to facilitate mounting and to avoid interference with the vehicle body. The conical shape of the rim profile (1.2) lends stiffness and enables the rims to be stacked for reduced storage volume in trunk.