Hy Roberts Big Hous, welcome, I believe the six bolt Budd wheels use an 8.75" bolt circle. So if you have a six bolt Budd wheels (use an inner and outer nut on the dual configuration) they should fit, hope that helps.
Below is the listing for 6 bolt Budd type wheels from the 1955-1950 GMC Master Parts Book. Your '58 would be an "S" in the "year series" column. Look for your serial number on the tag on the cab's left door jamb. There may also be a tag with the serial number on the inside of the glove box door. In either case the serial number will start with a 3 digit number that is the model number. In some cases of larger trucks there may be a letter code before the model number. In either case, use that information to look up the proper wheel type and dimensions in the chart.
By the way, "Viking" is a Chevy model, not a GMC.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Should be, but FX375F2356F looks like it has it has a few extra or misinterpreted digits in it. I don't think the X would be found on the original tag on the truck, and the second F should have been a P (from the Pontiac Michigan plant) or a C (from the Oakland Ca plant). You can find more info about the serial numbers and tags here OldGMCtrucks and the labels here OldGMCtrucks
I would expect your chassis serial number to be something like F375P2356F.
More info about your 375's running gear can be found in the front of the Master Parts Book. Here is an excerpt and a drawing from the same book.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
Robertsbighous Watch out for lefts and rights on those compound lug nuts,sometimes causes some cussing,stamped on end LandR. Have had to use smoke ax on em !!
