At the weekend I refurbed my rear discs by grinding off the wear lip with a belt sander and getting rid of the outer rust, I then sprayed the bits that rust with heat proof spray, they now look as good as new, I measured my new set which were 28mm and my existing are 26mm ( I cannot find a wear limit anywhere on any 260 literature ? )
I also measured the overall diameter of the shoes in various place and compared this with the measurements 2 years ago, I have found the shoe adjustment has not changed much at all in 10000 miles but the cables have stretched, to sort it I just tightened up the nut at the front ( which has a spacer behind and the handbrake is fantastic, when you fit a spacer remember to tape it up otherwise when you let the handbrake off it can rattle, just shows the cables do stretch
in a short time, and my car is only used weekends/ holidays .