same thing is happening to me... bmws come out of the factory with negative camber... but not to bad.... When the car is lowered it can/will cause the amount of negative camber and toe to increase which eats your tires really fast... Ways to correct it can be a 4 wheel alignment... but often times adjustable control arms (rear) or a camber kit is needed to bring the car back to factory specs for camber... If the car is lowered to much you cannot bring the car back and will need to either raise it up some, or get ready to buy a lot of new tires!
David