I usually try not to go below 26 lbs unless I really need to. That way, I don't have to suffer on pavement in between trails and don't need to air back up right away. The lowest I've gone is 20 lbs, but I ran Moab at about 26 lbs (or maybe it was 24 lbs?) and it was fine. For snow I would probably start with 26 lbs and then lower as necessary. That's my general rule; start at 26 and go from there. I run on the street at about 34 lbs, BTW. Oh...Pirelli Scorpion A/T's, 31".
