Underneath, it is an aluminum alloy wheel, but, as pointed out, there is a chromed plastic wheel cover permanently epoxied to the outer surface. I am surprised that no aftermarket supplied is offering replacement outer caps that can be re-epoxied on the alloy wheel once the chromed plastic gets curb-rash. I guess you would have to grind off the existing cap, and all of the associated epoxy. Certainly, there should be a different, less permanent adhesive - maybe old-style "wheel covers" ! But then GM couldn't sell $500 replacement wheels. LOLrickbb63 said:They are chrome clad. Somewhere on this site there is a thread about that. The outer chrome is plastic but built into the wheel permanently.