A safety system for a motor vehicle having at least a front wheel arrangement having one or more wheels and rear wheel arrangement having one or more wheels, the arrangement having: a control unit; and one or more vehicle inertial sensors to detect acceleration experienced by the vehicle, the inertial sensors being connected to the control unit so the control unit receives output signals from the inertial sensors; and one or more vehicle safety systems which may be activated by the control unit, wherein the control unit is configured to process the signals received from the inertial sensors and to determine whether at least one of the wheels of the front and rear wheel arrangements is not in contact with the surface over which the vehicle is driven.