I have a 328is and recently upgraded my wheels and tires. I had 16 inch rims and 225 tires but upgraded to 17 inch wheels with 225's in the front and 245's in the rear as recommended. Trying to save some money, I purchased brand new Falkens ZIEX ZE912 tires. After I got these tires mounted and balanced, I am experiencing humming sound from the rear...precisely at about 40/45 I get a low hum and at 70/75 miles I get a high hum but when I get to 80 miles the humming goes away...Does anyone have any idea what going on?? Someone said it might be my bearings but my mechanic said my bearings are fine and he thinks it's the tires..