The GM wheels are 6 lug. They're the transport wheels for all the new 1500 trucks that come with chrome 22's. The nice wheels are installed after the trucks come off the transport, and the steel smoothies are supposed to be sent back to GM.
I looked into these quite a bit as it would have been somewhat easy for me to convert my '94 C2500LD back to its original 6 lug configuration (I changed it to 5 lug), but after checking out the quality of them I changed my mind. Plus, didn't want the weight of steel wheels dragging me down either.
Richard