They've got stock Surly Knards 29x3. Fairly worn, but I hope to get at least 1000mi out of them before I have to replace. Oddly, the center tread knobs look in very good shape, as well as the extreme ones out to the sidewalls, but the median ones have all the wear. Maybe not much wear is applied to the center tread when rolling easy, but turning applies sideways force that wears those knobs out quickest?

Might replace with WTB Ranger, they're supposed to be fast-rolling, and everything is hard/dry here in SoCal.