Unless you're using a mortar and pestle while in your car - and really you shouldn't then you should never hear grinding in and around your car, especially when braking. A grinding noise typically means that your brake pad/shoe has worn out and you now have metal on metal for braking and number 1 that isn't safe and 2 it means that you will have to have your brake rotors along with your brake pads replaced.
We do a 52 point inspection that includes all of your brake components every single time we see your car. We make sure that you're safe to be on the road and on all your adventures. Your brake pads start around 10 mm, so when you get to 4 mm we let you know that you'll need to replace them in the future. It could be 6 months or 2 years, it just depends on your driving and the type of vehicle that you drive. They should be replaced somewhere between 2 and 3 mm, for safety purposes. Yes you still have a little life left in those pads, but I don't want to take the chance in you needing rotors too.
We do free brake inspections so if you are concerned about your brakes give us a call and let us take care of you.