Off subject 57 spear info:
https://www.youtube.com/watch?v=Gk_ZnYbFN08
Counted 16 on this page:
https://www.google.com/search?q=1957...ed%3B357%3B255
Wheel info:
GMCNut is correct:
According to Jim Carter the Chevy Cameo in it's four year run used Belair full wheel covers for 55 and 56, then used a ribbed trim ring in 57-58. The GMC Suburban pickup DID NOT use a trim ring in it's four year run, just a chrome cap. The wheel shown on the Suburban Pickup does have the extra squish ring feature. The Cameo wheels can not be seen in 55-56 (Full Cap), the 57-58 wheel does not have the squish ring. So if the squish is GMC and GMC had no rings and nubs are on squish rims; the nubs are non functional manufacturing features. (Clamping. indexing, forging)
Further, I have looked at 3 different Factory brochures for 1960 GMC. They are all artist renderings, not actual photos, so a little tricky. BUT: they show the potter wheel without the squish. So seems like the squish went away when Suburban Pickup went away and were probably used up in 59-60+ as replacement parts for 55-58 Suburban Pickups.