Auto Brake Discs 370*36mm J Hook New Center Bell For Megane RS4

Why do rotors get grooves?
Over time, grooves will naturally develop on the rotor from repeated contact with the brake pads. But these marks take away from the part's capacity to slow the vehicle, as well as cause vibration and pulsation that can be felt in the brake pedal.

Do I need rotors or just pads?
As a general rule, you should get your brake pads replaced every 10,000 to 20,000 miles to keep wear to a minimum. When it comes to your rotors, you have a bit longer. Your rotors should be replaced between 50,000 and 70,000 miles to keep your brakes in peak health

What do rotors do?
Discs or rotors work by pads that clamp down on the rotor to create friction to slow your vehicle. The pads indeed wear out first. The rotor's primary function is to absorb that friction. The more worn down your rotors are, the less heat they can absorb at one time, which results in longer stopping times

Your vehicle has one of two brake systems, discs or drums. Discs are also known as rotors. Drums are typically found on older vehicles, although some newer vehicles feature disc brakes on the front and drums on the rear.
The brake system is part hydraulic and part mechanical. The brake pedal is the mechanical system that begins the braking process. When you depress the brake pedal, you engage the hydraulic element. This hydraulic element sends pressurized brake fluid to the brake calipers. The brake calipers are like fingers that hold the brake pads. The pressurized fluid squeezes these mechanical fingers to close the pads over the disc. In a drum system, there are shoes inside the drum that push out against the drum wall to create the friction that slows your vehicle.