19mm socket and some muscle. Done it a few times on my car.
To get the wheel off, undo the nut, but not all the way. Sit in the seat with your hands either side of the wheel, and try to pull it off 1 hand at a time, so you are forcefully wiggling and pulling the thing. Thats what I have to do with mine, you cant pull it straight off, have to wiggle it. Leaving the nut on stops you pulling it off and smashing yourself in the face with it or something else unpleasant.