Are these 17 inch artillery wheels?
If they fit an original 1/2 ton 47 chevy, they will fit your 57 gmc without clearance issues.
I found some 16 inch artillery wheels several years ago to use on my 1940 gmc. The hubcaps from my 59 fit the centers without any modification. I had my 16 inch arty wheels widened to 7 inches, and plan to use either a 750-16 whitewall tire or a 235/85/r16 tire.
My current 59 gmc 1/2 ton has the 6 lug 15X8 ralley wheels from a chevy 4wd.
Here is a thread showing how to put vintage hubcaps on the more modern 4x4 ralleys.
https://www.stovebolt.com/ubbthread...ubcap+adapter&Search=true#Post834210