Random ebay surfing. They look like Torq-Thrust!!!! Looks like they came on 07-09 Silverado.
SET OF CHEVY SILVERADO GMC CADILLAC CHROME OEM 20" RIMS:eBay Motors (item 200340906665 end time May-17-09 13:00:29 PDT)
http://images.auctionworks.com/hi/60/59565/p507_020.jpg
