Which statement is true about disc brakes?

The statement that rotor thickness variation has a smaller tolerance than lateral runout is accurate. This is important because disc brakes rely on consistent contact between the brake pads and the rotor for effective braking performance. If the rotor has significant thickness variation, it can lead to uneven wear on the brake pads and reduced braking efficiency. On the other hand, lateral runout, which refers to the side-to-side wobble of the rotor, has a larger tolerance. This means that while some degree of lateral runout can be accepted without compromising brake performance severely, thickness variation must be kept within tighter limits to ensure safety and efficiency in braking.

Understanding the importance of rotor thickness and lateral runout tolerances helps in maintaining optimal brake performance and prolonging the lifespan of both the brake pads and rotors.