okay, if youve ever tried to put them on, you will see how the wheel hole is too small and needs to be machined out. if you do this, the plastic center cap wont have anything to snap on to, so you cant use it. but machining the wheel is the correct way to do this. what we did was dremel off part of the wheel hub by taking the dust cover off and dremeling. the wheel will sit flush, but the dust caps dont really fit on. this isnt thatr good because dust and other debris can get in the wheel bearings.