Perhaps a block of wood and a sledge hammer.
Sounds destructive but I have done this many times on steel wheels when I worked as a truck mechanic in the 70s-80s. I would stand the wood up so it would protect the wheel from damage then wack the heck out of it (hitting from behind the wheel). Usually one good wack would break it free. Of course you are trying to hit the wood directly in front of the steel rim (not the rubber tire, but many times just hitting the rubber would do the job). I would also spray penetrating oil in the wheel/hub area and around studs.
Another trick (I have not had to do this) that is said to work, is to back the wheel nuts off a couple of turns so they are loose, then drive the truck in "figure-eight" circles. I'm not so sure I like this idea but it is said tire shops do this all the time.