2003 530ia sport package. I just put two Bridgestone Pole Position tires on the rear and now the rear end is extremely loose. The rear end floats and sways especially when changing lanes on the turnpike. I can't believe that putting new tires on would cause the cars handling to south so much. The tires are rated "W" and my existing fronts (Continental ContiSport) are rated "Y". Should I ask the tire dealer to swap the rears to match the front? Is he going to try to take me to the cleaners by recommending a bunch of rear suspension work? One other thing, I looked under the car and a lot of the grease was rubbed off of the lower suspension parts. I don't see why they even touched that part of the car. Any suggestions would be greatly appreciated. BTW, car has 80K miles.