My 2009 Sonata has developed a 'rubbing' sound that seems to be coming from the right rear wheel. The brakes are new, the rotors are fine, there are no marks on the tire or wheel. This sound only shows up when I apply the brakes and generally at slowing speeds. If I press the brake pedal down hard the sound doesn't emit. We have checked suspension, brakes, rotors, tire and wheel. Ideas??