Prospeeder

The sensor goes off when there is still plenty of material left from metal to metal. Even then, you should be replacing the rotors anyway so who cares, it will still stop.

OldCowboy

As long as your rotors are within spec, there is no need to replace them.

SloopJohnB@mac.com

Here's the deal…Audi specifies a 1mm per side rotor wear limit. It effectively requires rotor replacement with every pad change.

But good news…just grind off the outside rotor ridge on the outer and inner sides of the rotor and slap in new pads. You can probably get away with 3-4mm of wear on both sides before the rotor gets too thin to function and even then it will probably function if the caliper pistons don't go too far out and ****/jam.

SloopJohnB@mac.com

On both my 2K4.2A6Q and 02S6 the rears wear out first. It could be because the rears are applied first and light braking (paying attention to stoplights, not tailgating, etc., etc.) then wears them out.

OTOH, if you use your brakes heavily then the fronts will wear out first.

Prospeeder

Problem I have is letting rotors wear thinner or machining them, your removing heat absorbing material. The thinner the rotor gets the more its going to warp and distort under heat, and you may end up with awful shake using the brakes and end up doing the job again.

tester123

I'd say grind them until it is metal to metal....just kidding. The warning light should give you a bit of time but I would replace them asap.

jcman

Don't be this guy