Is it lowered, and or on bigger than stock rims?
My 323i was lightly scrubing on the inside of the arch, so i had to play around with the camber a bit, from what u have told me, thats the only thing i can think of.
what sort of humming? it could be brakes, bearings, does it still humm when you go around hard corners? and or break hard?
let me know.