If the wheel is stuck to the hub, it is probably rusted tight. Put some penetrating oil around the studs and in the extra 5 holes in the wheel that have no studs. Let it soak a day or so. Then lay the assembly on a floor with the drum down. Put a piece of hard wood on the hub and hit the wood with a sledge hammer. It is easiest to remove rusted tight wheels while they are still on the truck by hitting them on the inner side of the tire with a sledge hammer.