I ride on lots of slick, rocky, tree-rooted single track around here and with the YZ's 19" rear wheel I was often worried about rim damage. Moto2000 (Scott) over in the WR section had an extra 18" WR wheel and we put together a cash/trade deal. I mounted up a tubeless-type IRC trials tire with a heavy duty tube on the 18" wheel for when I'm riding on the tight nasty stuff. I'm really diggin' the extra sidewall and I should be able to get away with about 8 psi...this tire combined with the Rekluse will be sweet on the trails! When I need a knobbie I can just swap wheels now.