I have 2 6500 series trucks 1955 and 1956. 1 has the same bolt pattern as yours (5 bolt front, 10 bolt rear), and 1 has the 6 bolt pattern. Both are 20" wheels. It was easy to find the 6 bolt 22.5" Budd wheels but I haven't found the other s in 22.5". I am told they are harder to find and are more expensive. They are out there. I would see if you can find any big rig auto wrecking yards. They might be able to help tell you what to look for.