Think I found my answer:

https://xoutpost.com/bmw-sav-forums/...eys-4-4-a.html

Vendors have been making them incorrectly for 80 mm when they should be 70 mm. Now I have to call around to some local parts stores...

Now I get it lol!

What you bought was part 17 as highlighted on the diagram. I thought you were installing it there too, but you were mounting it on the tensioner arm that has 2 pulleys, which takes the 70mm pulley not listed on realoem.

Good you found that thread, it seems to have part numbers for 70mm pulleys, hopefully they help you find the right ones for your application.

Autozone had the pulleys for like $15 so i'm good! Cars up and running nice and quiet.

Good to hear, thanks for updating the thread, it will help others in the future. :thumbup: