In the rare case people here don't visit the classifieds, I have a pair of 325/30/19 MIchelin PS4S FS there, perfect rear size for C6 Z06 (they came off my previous 09 Z06) and Grand Sport. Take a look there if you are looking for something for the back of your ride. I had the fronts too but they sold to someone needing them for his BMW so only rears available.
Tony
Tony