I run the Millville in rocks. It seems to hold up Ok. Best tire I have found so far for my local. Seems ok on dried clay hardpan but haven't tried it in wet gumbo clay. You can't expect miracle lifetime on the back of a 500. The K5 is definitely a tire eater. I notice my front Millville is a bit rock worn but it still seems to turn like new. I think a lot of tire choice has to do with your riding style and dirt type. My hero tire could be your zero tire. Alot of the new tires are cheap enough to try out then make your own opinion. I once had a Yokohama tire sponsorship - the tires were great, but only when brand new, a teeny bit of wear and they were horrible (but an unlimited supply). Guess thats why I'm good at changing tires: a typical week was, put on new tires, race once, flip the rear tire around, practise the week, wrench on a new set for next weekends race. Give the old ones away to friends. Ah those were the days.........Sorry to digress. Cam.