17” was standard on the AD 1 ton single wheel truck, not surprised your 56 3/4 ton had them too, but I’m not sure what sizes could have been stock.

19.5” wheels and 8R19.5 tires are a reasonable choice as well, several traction tires available. Goodyear G171 is pretty aggressive, I’ve run them before, and now have some G633 tires for the GMC, they also look nice.

•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-