Just had my S3 18K service (£250 which isn't bad I s'pose) and the only thing the dealer mentioned was that I should keep an eye on the tyre tread. Three of the four tyres had a 3mm tread depth but the right rear had 4mm. I asked if this was a sign that something might be wrong but the guy didn't really sound like he knew. He said if the car was a 4wd it might suggest a problem. I pointed out that the Quattro badge seemed to indicate that indeed I did have 4wd. Anyway, given he didn't exactly fill me with confidence does anyone out there have any suggestions as to why one tyre would be different to the rest. Also, he said the legal tread limit was 1.6mm but didn't know what the tyre depth was when new. Anyone know what the depth would have started out at. I am running Michelin Pilot Sport 225/45 ZR18's.