It isn't very loud, but it's there...It's a kind of chirping-squealing sound that occurs with each wheel rotation, coming from passenger side rear of the car. When I apply the even light pressure to the brakes, the sound disappears, then starts again when I let off the brakes. I had new pads and rotors installed, and this almost got rid of the sound (it was very, very faint at first and I thought it may even have been a different 'new-pads-and-rotors-related' noise...) but after just a few days, the sound had returned to its original volume. Any ideas?