Muncle

I took my 2002 C5 into ATS as one of my rear tyres was nearly worn out, We looked at the spare and decided to change it over as it had some more tread left, when I drove off the wheel was graunching and locking, I returned to the fitter and we took the wheel off and found it was grinding on the bottom corner of the caliper. We then decided to change the wheels back. But lo and behold the wheel I had taken off had a shiny wear strip on the inside! so I did not know what to do. I eventually decided to put the original wheel back which does not graunch. but I am worried about the wheel! Has anyone heard of this. were all C5 wheels made of metal because I had mine changed under recall 2 years ago and they said they were some plastic or strange Alloy. Looking forward to hear if anyone knows anything of this.