I have come to the point of needing to replace my tyres as I have a slow puncture on the back left and the fronts are nearly down to the legal minimum. However on taking a closer look today at the fronts tyres, the insides both have a grove worn into them and have heavy ware on the inside rim. I can’t understand why this has happened, there doesn’t appear to be anything causing this to happen, and I'm not a particularly aggressive driver. The tyres are run flats and are 20 months old having covered 22000 miles. I'm looking to change to non run flats but don’t want the same thing happening again. Anyone encountered this before or knows what is causing it?

