Here's what I do: (when bench-top mounting a tire) once the tire is mounted onto the rim I take a small pc of wood like a 1" x 2" stock approx 12" ....... once already having applied pressure with my foot against the rim pushing it into the other side of the tire I will take the wood stick and reach through taping the tire bead onto the rim seat, Once you have one side seated good take the wheel/tire and set it over something that will allow the wheel to fall through but still holds the tire from going through, I use a car wheel/rim,
As already mentioned remove the stem core and start inflating while pushing downward on the rim into the larger rim or what ever it is you choose to use, this will assist the sidewall of the tire to inflate into the other side of the rim,.... done it many times

it does help to have an assistant to put the air in while your pushing down on the rim,
If you choose not to try this

then get some blocks of wood 3 or 4 will do approx the size width of the tire a little wider will help, then wedge the blocks into the tire spreading the bead apart, lets set in the sun for a few hours, Hopefully the tire will loose it deformed shipping memory, :thumbsup:
Edit: I should also mention that its a good idea to seat the back side of the rim first, so's that the valve stem will be accessible at the top,
