[djpateman]

It could also be worn out brake pads. I have a brake pad where the caliper was seized to the point that the metal back was worn through, and the piston was wearing on the brake rotor. I'm sure it made a similar noise.

However, every part of the rotating assembly there is suspect. From stones caught between the rotor and the caliper to the splash shield rubbing on the rotor. Bad bearings (wheel and tranny), bad CV joints. There is a lot to inspect.