I use the Big Apple 2.15's for commuting on my 1996 GT Outpost MTB. They fit fine and there's enough clearance all around them; however, as someone else mentioned, make sure the 2.15's clear your frame.
Also, depending on how your brakes are set up, you want to be sure that if you remove your front wheel when you get to work, you have enough clearance to get it through the brake pads without deflating the tire.