If anyone has a problem with their 21mm socket not fitting their lugnuts properly (fitting rather tightly), either there is some rust/corrosion making the stainless steel covers bulge or the impact wrench at the tire store is mucking them up. These lugnuts are ~$5 a piece from gmpartsdirect if you have this kind:
These lugnuts fit on wheel number 2 for certain and maybe some of the other styles?
but you can get a whole brand new set of them here for ~$25 shipped:
http://www.ebay.com/itm/110462310003?ss ... 1438.l2649