Hog Wild,
The resource document at the GM Heritage Center for your
1946 1/2 Ton lists the available 3100 (1/2 Ton)wheel options, dimensions, and original tire sizes that would have been available for your truck.
I attached a screenshot below extracted for easier viewing.
Here is a resource page from the 1929-54 Chevy Master Parts Catalog
showing wheel dimension choices and original part numbers. Another screen shot below is added with the 2 standard wheel size options underlined.
Based on the parts book info, 15x5.5 or 16x4.5 standard 6 lug wheel for 1/2 Ton trucks from '38-54 will fit your '46 (all the same part numbers), depending on which of those sizes you choose. There are still 16x4.0 wheels around out there, but Chevy evidently did away with listing those in the catalogs as the 16x4.5 width wheels became the standard for later years.
The 16" wheel and the tire mentioned by Otto above does fill the wheel well opening nicely and the radials are a distinct upgrade to bias ply tires of old.
Hope this is helpful!
Dan
