So I go to my HHR this morning and find the tire is flat. I got to try the roadside assistance thing in the warranty and they come and put the spare on for my GF. She takes it over to a shop to repair the tire and they find a steel shaft 5" long and 5/8" diameter inside the tire. Whoa!!! We don't know what it was from but it was highly polished machine steel like an alignment pin for some press or molder. Kinda resembled a 50 caliber shell.