You will get a million different opinions, here is mine.
Anything that is bare minimum a 4ply if in the rocky shit. I will only run a 6ply around here and i use Rzr2's. Decent grip, last a long time, going on my 4th season with them and i ride the road a bit here and there, a bit on the heavy side but won't t pop and leave me stranded 40 miles into the mountains(done that before ). Ive been using tire foam inside my wheels for last year and this year for peace of mind too.
There are a bunch of knock off raz, holeshot type tires out and around, im going to try the ambush tires next i think.
Ive popped quite a few 2 plys like dunlops and stuff, they hook great but in my experience where i ride, they don't last long and are too soft for me.