Tires are or were sometimes described by nominal outside diameter instead of rim size.

Are they by chance 20” rims, measured where the tire bead seats or contacts the rim?
looks like it to me.


•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-