Hello! For my first post I'm probably about to kick up what seems to be an ongoing uncertainty around Audi forums! Got myself a MY10 A3 Sportback 170PS 2.0tdi quattro BE just over a month ago and I've just noticed these cracks on both rear tyres on the tread/sidewall transition and circumferentially on the inside tread groove. Running Bridgestone Potenza RE050A 225/40/R18 92Y. I am uncertain of the tyre usage from the previous owner or what comes as standard on these models, however the car was barely used by the previous owner (12k miles when I received it). Wondering what people's thoughts are on this, advice with changing tyres on quattro systems with regards to changing axle pair/all 4 corners, different brands front/back, recommended tyres? Will probably be going to a local tyre shop to get a quote at the weekend Any help will be much appreciated. Will hopefully get round to a happier hello post with some nice pictures in the near future! P.S. Very good forum.