What is my next step in figuring out the root cause of a steering wheel shimmy

Question

I have a 2006 BMW M3. Since I put on wider wheels with wider tires in the front for track use (from 225 19" to 255 18") there is a wobble / shimmy between 70-80 MPH that can be felt in the steering wheel.

Putting the old wheels back makes the vibration disappear. Swapping the wide wheels between front and back does not help.

• I had the wheels/tires re-balanced 3 times. Makes no difference.
• I had the car aligned. Makes no difference. Caster is off (too much positive) for an unknown reason. I don't know the amount but it wasn't alarming.
• The front rotors are dragging a slight bit, the driver side is worse. The driver side wheel gets dustier.
• There was something looking like oil on the top of the front left strut, but it could be mud. I cleaned it and will see if it comes back (if the strut is leaking)

Here is a video of the inner tie rod end, while shaking the wheel at 9-3 o clock with steering wheel locked. https://drive.google.com/file/d/1lgChxJvxHnvQZqOiZ7fhxOYvM6lmJOLh/view?usp=sharing

I can't see much play at the tie rod end although the steering rack is moving a lot, is there any play in the joint? Why is my steering rack moving this much?

One of the wheel is not perfectly straight but it's very slight. Here's a video: https://photos.app.goo.gl/SRaqHiaHmDcGp4pW6

What should I start with?

Answer 1

I think the obvious source of the "shimmy" is the rim itself. If the rim is not completely true (which the one you showed is not), it will most likely be felt at the steering wheel. This probably won't affect your performance, but it will affect the feel.

There's an easy way to tell if there's too much play in a tie rod end ... that being, is there any play in a tie rod end? While this is probably not the source of the shimmy, it my be exacerbating the shimmy (making it worse). This is definitely something which needs to be fixed.

I created a video a while back on what to look for with tie rod ends and how to tell if they are bad. While I agree this is self serving, I believe it is pertinent for your issue.

https://youtu.be/JfciZNJl38Y