The most popular RPM wheel the Revolver has made the transition into the Monster Truck market! These wheels are the most realistic off-road truck wheels RPM has created. RPM Revolver Monster Truck Wheels have been designed with either a 14mm or a 17mm hex drive option to suite your driving style and drive preferences. The 17mm hex drive is fast becoming the most popular drive option, especially with Truggy drivers due to its naturally stronger ability to resist spinning of the hex. Both the 14mm and the 17mm hex drive versions are backed by RPM s renowned breakage warranty and all RPM wheels are tough enough for serious backyard bashing, yet light enough for competition level driving!