I'd put some RE spacers 10, 12 mm on my Z4
http://www.e90post.com/forums/showth...spacer+warning
and when I pulled a wheel to check brake pad thickness I noticed a crack on one of the spacers large enough to see light through.
this was after 1 trackday on stock tires, stock suspension, stock power, mediocre driving ability.
I promptly removed all 4 spacers.
just wanted to throw that warning out there with the RE aluminum spacers, you may not want to track/autoX them.
I'd run spacers in the past and had no issues, they were the standard ones tire rack shipped me with a set of wheels, and had sturdier material around the hub center.
I think there was a guy on here who's space broke and sent his rotor through his wheel........