You can increase the size of your rear idlers and not cut your rails. These are a simple bolt on. You can go from a 6.375" wheel to an 8" wheel or from 7.25" to 9". You have to have an adjuster that pushes from the front and your axle slot has to be 1" high. These will fit Polaris, Yamaha, Arctic Cat, and Ski Doo. This does not fit the XP rails. These are to be used with two outboard wheels and one or two inboard wheels, 25MM inside diameter bearings are required in the wheels.