in another thread I had two rims replaced due to tiny tiny cracks. I did not know they were cracked, they were not at this point leaking air. I'm pretty careful and never hit a pothole... GM covered them under warranty... I think because there is a class action lawsuit in the States because so many are cracking.
They would have been about a grand each.
I was talking to one of the guys from the Manitoba club last month. One of their members that we all met at Meet In the Middle had to get his Z06 wheels replaced.