i'm running XM819 rims, and i've been using for most of the time since i've changed to tubeless, IRC serac xc tires, along with stan's sealant, and lately, joe's no flats. during my recent tire change, i observed that my much older 2.1" tire probably had the bead a little stretched out, and it was a bit of a problem to inflate up using even my floor pump - can't imagine having it giving me problems on the road. i'll bring along at least two tubes and some patches to work around the "air leakage because the bead's not sealing on the UST rims properly" scenario.