Ratchet strap around the circumference (outside) of the tire. As you tighten the ratchet, it should push the beads out toward the rim.
I haven't needed to do this in many years. I would stop adding air, and release the ratchet as soon as the tire would hold pressure.
dirtybike screwed with this post 01-21-2013 at 04:34 PM
Reason: Additional info