It's definitely something to do with the rotation of your wheels then. I once got a crushed beer can stuck in between the wheel and the brake caliper.
I'd suggest a good visual inspection. If metal is hitting metal, you must be able to see something.
Nick / TopDownInFL (sans the "top down")
2012 650 Coupe - Alpine White / Black Interior / M Package / Premium Sound
2008 650i Convertible
2004 645Ci Convertible - Reverse Sensors / Reverse Camera
2005 545i Sedan
2003 330Ci Convertible
2001 330Ci Coupe
1998 323i Convertible
1995 318i Sedan