Front discs & pads...

[Markp]

Outer "holes" on edge of discs are wear indicators for discs....once hole isn't visible anymore(worn down) this is indicating time for change.

Thanks Chris

[Nigelo2]

For the Brembo wavy discs:

Front 19" dia: 36mm new / 2mm wear limit / therefore 34mm is the minimum thickness
Rear 17" dia: 22mm new / 2mm wear limit / therefore 20mm is the minimum thickness

hope this helps