Let's say you take off the wheel (when replacing the pads, for example) and look at the brake rotor. What are the signs that it's time to replace the disc?
Let's stick to clear visual signs that don't need extra special equipment or driving the car and listening/feeling to notice, such as slight warping.
A couple of examples that come to mind:
- Low thickness
What else? Is rust dangerous? Even if you have a single sign to add, don't hesitate.
Example pictures along with written signs would be extra helpful!