Final answer:
Disc brake rotor run-out tolerance is approximately 0.1 mm, necessary for optimal braking performance and preventing pedal pulsation and uneven pad wear.
Step-by-step explanation:
The tolerance for disc brake rotor run-out is approximately 0.1 mm. Rotor run-out can lead to brake pedal pulsation, uneven brake pad wear, and overall reduced brake system performance. Manufacturers will typically provide a specification for maximum allowable run-out, which is measured using a dial indicator while the rotor is mounted on the vehicle. The specified tolerance ensures that when the brakes are applied, the rotor remains as true as possible, preventing brake judder and ensuring optimal contact with brake pads.