The sound appears to come from the front whenever I brake harder than normal. It sounded like someone is playing a trumpet from afar...broop...broop...boop boop as I come to a halt. Also sounded like a trombone at times. It doesn't come on all the time but most certainly when I brake moderately to harder than usual. Bought the vehicle at 36,000 miles and now at 51,000. Could it be the front brake pads and rotors? The pad seemed to have some meat in it but not sure when it was last replaced. I can also smell something burning around the wheel, probably because I was doing some heavy testing to probe the noise. Also when I checked online for rotors, there are choices for either 300 or 320mm with 15", 16", and 16.5"??? Which is it? I have 17" Spartacus wheels.