can anyone give me a rough idea of how quickly a cars brake discs can wear down? I had my service and mot done Friday and it was picked up that my discs had developed a lip round the edge, and were heavily corroded and scored. they said in that condition were dangerous and would fail the mot. got new ones straight on but when looking back at a health check I had done at the same place in august, the discs and pads showed no concerns. the car has only done 2000 miles since then. am I right in thinking that discs so badly worn would have showed damage at the health check? surely it would take more than 2000 miles for them to get into that bad condition?