I have found multiple PNs for these wheels same design. The 1s described for WT wheels are selling a little over $50 a wheel as the spares are $130 or more for black, silver, and 1 with no mention. Steels should be 17x8 and the aluminums i have found sellers/forum members are saying 17x7.5 anr 17x8.
I know my K2XX are 17x8 steel take offs i have and aluminum were 17.x7.5 spares.
Part #s i have found
Gm steel wheel part #s
86508934 black not sure of what material
84947816 aluminum spare wheels
84440191 silver steel spare wheels
560-08130 Black steel spare wheels
84927607 stock front and rear steel wheels
The last part # 84927607 are selling at dealers online from $48-80, locally my search shows $60 cheapest. All the other wheels are almost 3xs the price.
Personally I like the looks of the steel wheels better than most aftermarket steel wheels. Even the aluminum spares look good, just they probably wouldnt be a good wheel to tow up to 10k lbs with being a cast wheel from china dependent if there is an actual load rating for them around 2300lbs. Or so. Example of the steel wheels repainted on a GX470