What works for me is to put the tire & wheel flat on the floor but with the wheel raised up on another wheel or block so the tire will "hang" down on the lower bead. soap up a bike inner tube, put it under the rim's bead that is now facing up & inflate it to fill the gap between the wheel & tire. Remove the schrader valve from the stem to increase airflow & air it up. The trick is to get the tube to slip up & out without getting pinched in the bead. With a little experience, it will become very easy to do.
