Actually, on slick rock (Moab) AT's do quite well. The tires on that buggy are not so good on the rocks. Those tires are probably the best you can get for strictly mud. Most that do use those swampers for other options end up taking a tire cutter to them. For rocks you'll find nothing better proven (in comp.) than the BFG Krawlers and the Maxxis Creepy Crawlers...both of which also do exceptionally well in Moab also! My biggest concern with nearly all AT's is the relatively weak sidewall. Big, sharp rocks around here tend to shred/cut/tear them which is not a fun time in my book.