A castor wheel for a vehicle or an attachment for a vehicle, the castor wheel comprising; a wheel having an axle about which the wheel can rotate, an offset pivot mounting for mounting the castor wheel to the vehicle or vehicle attachment, the pivot mounting being connected to the wheel axle and defining a pivot axis perpendicular to and offset from the wheel axle, the wheel capable of pivoting about the pivot axis, and wherein the castor wheel also comprises a restrainer for restraining the pivoting of the wheel is disclosed.