Start by removing the valve core.
I have been known to jack my pickup truck up with the floor jack, place a block of wood between the frame and my aircraft tire, then slowly lower the truck till the bead breaks away from the rim. Usually have to do this on both inside and outside of the tire.
Be carefull not to bend the brake disc. I have been known to use wood on both sides of the tire to keep the disc from touching the cement floor.
Care must be taken to make sure the tire and wood does not fly up and hit you or the airplane.
This technique wooks well if you know what you are doing and recognize the dangers. I hope I wrote the info down that you can understand what I do and are able to make sure it is the right way to do it for your airplane tire.