knocking sound, coming from ...?, anyone know what it is Options

[xRaveNx]

recently since ive noticed that my clutch was going, i also noticed a sound that seemed like it was coming from the rear tires, gets louder the faster i go, i checked the front tires, doesnt seem to be the axles or CVs. It sounds like a hard metal knocking sound as if someone was pulling back my plastic pieces in my wheel well and letting them slap back into place, idk if that makes sense. I was wondering if anyone knows what this is or what I should do? thanks

[TrdKing]

when does it happen?
braking?
speeding?

tell us driving conditions

[djyohimbe]

If you have a sunroof it may be the drian tubes that are located in your blind spot, behind the panelling. I had that problem and had to take everything apart and put some fabric where the tube was knocking against the frame. The plastic gets harder over time and becomes audible.