Intro: Grinding noises usually mean something is rubbing or worn.
1. Brake pads
Worn pads grind on the discs.
2. Stones in the brakes
Small stones cause loud grinding.
3. Wheel bearings
A worn bearing grinds while driving.
4. Gearbox issues
Grinding when shifting = clutch or gearbox problem.
5. When to stop driving
If the noise gets louder, stop and get help.
Summary: Most grinding comes from brakes or wheel bearings.