Hi there, looking for some advice on the tyres for my Cayenne S 2007 4.8. I have replaced the front tyres yesterday with Summer Pirelli Tyres. However, I was told by the tyre fitter, than I would have to also change the rear tyres even though there was tread still on them, because they are winter tyres. He said that because he said if I didnt it would damage the differential and I would end up with all kinds of warning lights coming up on the dash board and would need taking back to Porsche to be reset. Because, the tyres all need to be the same, i.e. summer tyres. So at present, I have Summer tyres on the front and winter on the back. Will this cause any kind of problem or damage my car in any way ? Looking for concrete answers from somebody in the know and not just a wild guess. Im just loathed to fork out another five hundred quid for Summer tyres on the back, when there is nothing wrong with the Winter ones on the back. They have plenty of tread left on them. I would add, I bought the car four months ago and the four winter tyres were on it at purchase. All advice gratefully received. Will it damage my car in any way to leave as is, i.e. Summer on front and winter on back.