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.
I have heard of guys having clearance problems with the fenders & steering radius when installing 19.5's on 1 ton trucks.
The two piece 15" and the three piece 17" were the original rim choices for 3/4 & 1 ton trucks.
{16" were also avail. but only on dual rear wheel equipped trucks}.
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