1.Simply apply compressed air to the open valve stem until you hear the bead ‘pop’ twice. The popping sound is when the bead is pushed onto the rim, locking the tire in place.
2.For larger tires, the bead may not touch the rim, so you can tie a loop in a rope, and pull on the rope to help force the bead outward against the rim. While you pull on the rope, apply compressed air to the open valve stem until the bead pops into place on both sides of the rim.
3.If all else fails, spray a small squirt of starter fluid to the interior of the rim with the tire roughly in position. Use a BBQ lighter (keeping fingers away from the rim, having a compressed air nozzle in the other hand) light the starter fluid by the edge of the rim. The expanding flame and gas will almost immediately pop the bead into place, and the tire will start to deflate very fast. Quickly apply compressed air to the open valve stem, which will prevent the bead from breaking loose again. This method works very well for me, but should be done with caution. If you are at your wits end, you can always take your tire to a shop, where they can professionally inflate it.