That's a cute truck, I like it.

The wheels are easy, they are "Dayton" style and probably 20", and new or used 22.5" Dayton wheels are a direct replacement.

Check the width of the new wheels, as you need them to be the same or will need a new spacer ring between the duals to account for it.

Easy and cheap to find in junk yards.

This catalog shows what is available new, and what you should look for used:
http://www.accuridewheels.com/completeversion.pdf


Personally if the wheels are the three piece lock ring type, and I did not want much money in the truck I would leave the wheels alone, it is perfectly acceptable on a truck that size to use 20" lock ring wheels.

Grigg

•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-