Are your tires new? The first place to start is the tires/balance. However there may be still be vibration problem even if they are in balance. Find a auto/tire service that has an Hunter 9700 road force balancing machine. This piece of equipment will find a problem tire which in your case is most likely one of the front tires. If you have after market wheels on your vehicle that could be a problem too. BMW wheels are centerd on the hub and if you after-market wheels on a BMW, you must use hub-centric rings in the center of the wheel in order for the wheel to be centered on the hub.These rings could paper thin. Also a lot of the latest OE wheels and after-market wheels take clip-on weights on one side of the wheel only and stick-on weights inside close to the outer part of the wheel. The Hunter machine is extemely helpful in dealing with this type of set up. How do I know all this? I have been in the business for 18 years and deal with vibration issues every week. Hope this has been helpful to you.