Y'all can still run 20" wheels from about 56-59 (and later?) trucks as well as 22.5" wheels if you can find them, same year range.
Older wheels can have the center bored out to fit 5.25" hub.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-