When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
AFAIK, no C5s came with recessed ends on the lug nuts. I think you've answered your own questions; probably none of them are correct. Base C5s have the GM gold colored nuts with external threads, so the plastic "chrome" nut covers have something to screw on to. Not certain what the C5 Z06 came with, as I've never owned one. Chrome caps are not cheap, and are kind of a pain, really. If the nuts on the 3 wheels are in good shape, I'd try to match those up on the 4th wheel, which you've said has one of them now, and be done with it. If not, I'd buy some McGard lug nuts. Not cheap, but it'll be the last set you'll need for the car. Hope this helps.......
The ones with the "sunken" face look like they got stuck in a socket. They were knocked out of the socket with something and that's how they got dented. The single one with the 11/16 hex (also likely a 17mm) is just a replacement that was available at the time. Its likely a 17mm hex because the threads are metric (m12x1.5). Alot of times the smaller hex ones are used on aftermarket wheels with a smaller lug nut hole opening. The missing 19mm hex lug nut is probably still stuck in the socket.
Last edited by chain_5001; Oct 9, 2021 at 09:52 AM.
I've run sets of chrome acorns from both Amazon and McGuard. Both work just fine at nominal power levels, and look matched from lug to lug and wheel to wheel. The Amazon set ran less than $30 for all four wheels.