Abstract: An apparatus (102; 202; 302) for preventing the skidding or sliding of a wheeled vehicle on a road surface (164), and the apparatus comprises an annular element (106; 206; 306) defining a first central axis (a-a, a3-a3) and having an outer wall (108; 308), the outer wall extending around the first central axis and facing away from the first central axis and being provided with friction means (110; 310) arranged to engage the road surface, and mounting means (116; 216; 316) for mounting the element to one of the rotatable wheels (116; 216; 316) of the vehicle and around a second central axis (b-b, b3-b3) defined by the mounting means, the mounting means being arranged to be attached to the wheel so that the second central axis is substantially collinear with an axis of rotation (c-c; c3-c3) defined by the wheel and so that the mounting means and the element are rotatable, and the element is movable in a direction about the first central axis in relation to the mounting means, wherein the mounting means and the