I sit on the ground, facing the wheel and kick my legs outward at the edge of the tire. You could also try rolling a loose wheel/tire into the same area (but watch that you don't hit the body). Basically you need a strong force and the leverage there of (why you hit the outer edge of the tire) to jolt the wheel loose. Do this at your own risk.

 My wife had a Dodge Intrepid and every 5K miles that I rotated the tires I had to"kick" them loose. The steel and aluminum seems to super glue themselves together quite well.