Plan on new rotors next set of pads.

The ridge is a result of the fact that the pads don't cover the complete surface of the rotor -- I suspect so that crud and rust don't interfere with braking.

I've never seen rotors on an MB that were anything but pretty smooth until they are worn out -- wavy, but not grooved. Very rare for someone to actually run the backing plate down to the rotor, anyway.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!