|
Wheel bearing(s)?
They are non adjustable and normally on late model BMWs make a rumbling or howling noise before a higher pitched noise like a squeal. Heat does also make the noise more apparent. The most common mode of failure on these cars is lubricant failure or impact damage. Both result in surface damage to the races.
Have you noticed any inconsistency in your brake pedal travel? If the bearing is loose then the disc would shimmy with the wheel, pushing the pistons back on opposing calipers such as these
|