Recently installed Heidenau Scout K60s . . . don't have much history, but . . . the big boys on the playground say they have amassed impressive mileage.
Greater, I think, on the wider (rear) tires with the continuous center strip (the treads vary somewhat with width).
Still might not be cost-effective, in comparison with, for example, bargain-priced Kenda K270s. The Heidenaus cost plenty.
BTW, I have a brand-new, never-mounted Continental Trail Attacks set looking for a home; no one seems interested. One guy did, but he ran, screaming, from the room, when he discovered these a TUBELESS tires; didn't want to put a tube in a tubeless casing . . .