The other day, after driving 50 kilometers, my tires were making a metallic grinding sound after exiting the highway. The next morning I turned on it was gone and it hasn't happened since. I checked struts, CV, brakes and it all looked well. 2011 Mazda 3.
Noises can really be annoying but if you heard a metallic grinding noise, then generally, that’s metal on metal and you are going to see shiny things where it is rubbing. So look for shiny things near the area where the sound is coming from.
Also, what sometime happens is the rotors just get old and they get shiny and the brake pads crystallize a little and start making grinding noises. So, if you pulled all your wheels off and you saw all the brake pads are still thick, the rotors don’t have a bunch of gauges in them, and they are just shiny, then it’s probably the best to just live with that. A lot of cars get that when they get age. And, if that noise bothers you, then change the rotors and brake pads and use high-quality brake pads, like Akebono brake pads. Akebono is a Japanese company. They make really good brake pads that don’t make any noise at all. To be sure, you can have the car noise inspected by a professional mechanic to ensure that you are making the right repair.