i found wheels for my 56 off a fed-ex truck that was being scrapped out.it had 22.5's w.7.50 tires.
cant remember the year but was an older truck
What was your bolt pattern? 6 lug Budd I'm guessing? if so these can also be bought new, see part numbers a few post up.
58GMCnut's 56 1 1/2 ton Chevy dump likely has 10 lug hub centered on 7.25" circle, in which case new wheels are not available, but check the tech tip for your options.
Grigg