When I rode bikes, I would change my own tires all day long. ATV tires are a bitch. I can't even break the bead.
Use the rounded end put it so you drive it toward the rim then as you hit it pull it toward you that will force the bead down. Then move around next to where you started keep repeating until it breaks loose. make sure you do this on the short side of the rim.I tried everything, I even put a board on it and drove my truck on the board... couldn't break it for the life of me.