They tend to get loose as you remove them to change a tire and then fall off while you are driving and people that buy used BMW's sometimes never get to see them because they are already lost, I got tired of buying them and forgot about them, some come with BMW lettering others just plain. Here's the pic and part #

I remember this issue being discussed some time ago. If I remember right XMeister offered 2 types of lock nut cover caps, with links. Can't find them at present though, sorry.
Below is a close up of mine. GL Moh :thumbup:

Thanks for the picture. Yeah I checked my wheels all of the lock nut covers were missing. I don't ever remember seeing them either. Looks like another trip to the dealer for me:stickpoke

Hey, I want some! I had no idea that I was missing them. Are they chrome or black? I've never noticed them on other X's.

Mine and a few others that I've seen are black, the cap is made of hard plastic. I often knock one off when washing the rims, somehow though they stay on no matter what the speed and or conditions.