I have had to take a 5 lb sledge to mine now I apply a thin coat of anti-seize to the rim before I put it back on.

 

I had the same problem. Rear wheels hadn't been off for 5 years or so; they were good and rusted on. I used a come-a-long and length of chain to pop it off. I had applied wd40, liquid wrench & pb liberally 2 days earlier. Had tried the chuck norris method and the drive-back-and-forth method nothing worked until the come-a-long popped it.

 

Have used like a 4 pounder & block of wood on rim with success on an old truck I had. Went around rim like 2 times in 4 different spots before it just popped off.

 

Photos for the come-a-long solution are here.

 

OMG people ,you are making this much too hard. Take all the lug nuts off,put one nut back on loosely, use a recoilless hammer, and beat that damn rim till it comes off.