I'll pass on a few tricks to bare-handed tire installation. Mind you, it can still be painful. Follow Spokewench's advise about letting out any air in the tube and squeezing towards the middle. For that last bit, body position and proper leverage are important. What I do is squat and lay the wheel flat on my legs with the recalcitrant tire bit up and away from me. Then work the tire on with the middle of your thumbs, using both thumbs close together (thumb tips 1 inch apart) to work over a piece of tire and moving around the rim until the last bit is on.

This technique has never failed me except in the early 80s when narrow high pressure 700c clinchers first came out and were an extremely tight fit to the rim. Then I occasionally resorted to the VAR tire lever/installer (see http://www.sheldonbrown.com/var/pages/var0051.html item 425). This little gadget lifts rather than pries the tire on. Too bad it's no longer available (but I have 2 of them). You
can buy this:
http://www.biketoolsetc.com/index.cg...&item_id=KS-TJ
but it's 9 inches long and you wouldn't want to carry it on the bike. But really, bare hands are always best and with good technique most any tire can be installed without tools.