Q: whining noise on the rear passenger side near tire

Hey there,

In regards to the whining sound that is coming from the rear passenger side on your 2003 BMW, at first glance, this type of sound could be caused by a wheel bearing that is beginning to wear out or a problem inside the rear differential. However, the sound could be coming from the tire as well.

Most BMW’s have directional tires and it’s not uncommon for the tire size to be different on the front and back of the car. Due to this fact, rotating tires, and ensuring proper and even wear is very difficult, which can create a tire cupping situation - especially when the rear struts are wearing out. Cupping on a tire can cause a bumpy ride, but another common side effect is that it creates a high-pitched harmonic "humming" sound. The way to detect if it’s a tire issue or a problem with the wheel bearings is to have an ASE certified mechanic take the vehicle for a test drive and begin the diagnostic process for the car noise.

This is something that might be annoying now, but if gone unrepaired could lead to additional damage or an unsafe driving situation. I hope you’re able to find a solution to the problem sooner rather than later!