I just gave my wheels to my LBS wheel guy to work over. He told me that he could tell that I've been doing stairs b/c my wheels have some flat spots in them. I usually only run 35-40 psi when I ride trails. I didn't air them up any more than that when I went out to the stairs the other day because I'm a freakin' bonehead.
I'm 6'1" 185 pounds. He said I should be running 50psi. I'm running 2.1's and I really should be on 2.4's for that kinda stuff. I think I'm going to get me some of those Kevlar Panaracer Fire FR pro's 2.4's.