my friends dodge caravan is making a metallic sqealing noise from the front driver's side wheel whenever he turns left. its not the brakes, thats another independent squeal. wink anyway, any of you guys got suggestions? what could be making that noise?

96 Contour SE, MTX
2 Pioneer 12"s in a bandpass box
2 5x7 Pioneer Plates
2 Stock Speakers
600 watts of blistering radioshack power