I just had my 2wd Xterra lifted 6"!!(3"susp. and 3" body). Im running 33x12.50 bfg all terrains. I had to do some trimming in the front wheel wells but i now have no rubbing issues! I havent noticed much power loss running the bigger tires nor gas mileage loss.

I took it offroad yesterday, nothing serious though, just a little mostly flat dirt trail. But just as the other guys have already said, it just depends on the terrain. Serious rock climbing, deep mud, and sand are the types of terrain i would NOT suggest!

Im posting pictures as soon as i get the scanned!