sure they make them in plastic, and unless your using rail extensions built for bigger wheels, or the offset axles, you can only go to a 7.5" wheel on a yamaha. You also will need to grind about 1/8th of an inch off the axle spacers, cause the wheel bearings are thicker on the older 7.5 wheels then the newer srx/viper wheel bearings, the mod works very well along with chainging all 6 of the small black idlers to 5.350" units.