A trick to always remember when changing tires is to loosen the nuts when the car is still on the ground, before you jack it up. Just loosen them so that their locks release, then jack up and remove the wheel. If it still won't work, take off all the nuts and SLOWLY let the car down, until the wheel gets a bit of weight on it. Jack it back up and see if the weight on the unbolted wheel released it. If not, get a cloth and tie it around the wheel spanner, and stick it into the wheel's spokes. Pry off the wheel with the spanner. The cloth is so you don't damage the wheel/mag/rim.































PS, removing that big nut will cause a LOT of trouble, do not touch it! Also, be carefull when removing the tire to not hook the brakepads, as this will cause the breakfluid leaking out and the brakes will then have to be bled, etc. etc.