RoadKing big-bore 2.5 inch shocks are designed with trailers in mind. Unlike OEM & replacement shocks RoadKing offers twice the bore size which translates into 4X the control and dampening force. Controlling the truck and trailer requires this force, especially at higher speeds. RoadKing shocks provides this force increasing the stability, safety and an over all more comfortable ride. RoadKing shocks, by keeping the tires on the road longer, slowing down transitions such as pot holes, railroad tracks, etc, will improve your tire mileage by up to 30%.