This is the souce of a lot of the info I post
https://www.gm.com/heritage/archive/...formation-kits
Scroll to the chosen year and open the pfd.
57 is the last year that shows those tire/wheel charts with 58 and 59 just listing tire sizes per gvw in the specs.
That 58 wheel that the photo of is a little over six.
I've seen those Hode podges of wheels on these trucks a lot.
I've never kept 16 inch six lug wheels around unless they had tires good enough to be decent rollers to tow a hulk off to where ever. I can't remember exactly what I did with the ones that came off my 48 in 1973 but I think I gave them to someone in town (McGregor. Tx who stopped and asked about them after I had the 15 inch Z28 Rally wheels on it.
I couldn't say without going out and looking at it if the wheel outside with the clips is 15 or 16 and don't know how wide it is. It will find a new home some day when someone local needs it.