265/70/R16 is equivalent to a 31x10.5. 265/75/16 is equivalent to a 32x10.5.
I second the nomination for the Revos as a great AT tire. I have BFG AT/KO's and they are great too. I'd say the revos are a touch better on-road and the BFG's are a touch better off-road. Price wise I think they are pretty close (assuming you get the heavier-duty Revos which are equivalent to the BFG's). I have the BFG's and that is my preference between the too, but you truly can't go wrong either way. The Yoko Geolander AT's are quite a bit cheaper, but don't last as long (I've heard) because of a softer rubber compound - but this results in excellent wet traction.