Just went through the same thing recently. I found an off-the-beaten-path tire dealer who had decades of experience. Some of the tires were fused from rust/time to the rims (some of the tires were date stamped in the 50's). They poured gas on the beads and let soak for ~30 minutes. This initially freaked me out as I thought he was going to light them! He then used a specialized portable bead breaker and worked around the circumference of the tire. Then he turned the tire over and let the young guys hit the other side of the tire bead with a duckbill until the seal was broken.
On the first rim, I had concern that they would not be able to do the job but they developed a process. The rims turned out to be in relatively good shape considering that they are 70 years old. I left the tire shop in good relations with the crew, and they are willing to work with me in the future. Everyone learned something that day.
I advised them that when I returned, I would have fresh media blasted/primed rims and new pliable tires. They all thought that was a good thing.
Paul
