I had this problem on my A7 in August 2020. Both rear tyres failed the MOT with 5mm tread due to inner side wall splits (as shown in other posts). Audi Worcester informed me it was common on the A7 and suggested changing to Pirelli in future. Apparently it is due to the lateral movement of the car causing the sidewall to deflect and split. Sadly my wife had passed away 2 days before and I had them replaced without making any fuss. In hindsight, I should have retained them but do have the dealer service video. It's going in for rear brake pads on Monday and I've asked for an inspection report. It's clear that the Dunlop Tyre has a manufacturing/application issue.
