Well i searched and searched and did not find anything so here is my delima. I am about to buy a new WR and I really want a X but I would want a set of 21/18" rims for dirt got a little boy who likes to ride some times but the bike will be on the road most of the time riding to work it is 50 mile round trip on twisty 2 lanes. Could I get a set of rims for the X where all I would have to swap is the disc rotors from them back and forth ( going from 17" to the 21/18" combo). If so do I need actual R rims or would I have to get a set built or would some other YZF rims work rotor and all what are my options (cheapest option). I want two sets of rims no matter what route I go. One for dirt only and one for street.