Your best choice is going to be 19.5" wheels with probably 8R19.5 tires.
I have had this size on my 52 1 ton and think the size looks great. See pictures on my link.

Wheels are available at junk yards, start by looking for single wheel bread trucks. They are also available new at http://www.ricksontruck.com/

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-