Originally Posted by ThermionicScott

Rather than using levers to pry off the tire, try getting all of the beads into the center well, grasping the tire in one spot, and pulling it laterally until a bead comes over the rim sidewall. That's not a great explanation, and I'd like to make a video or something someday, but it works well for me when dealing with tight or really stiff tires. It's annoying to my "just use a tire lever!" friends, but I nearly always triumph in the end.