Originally Posted by rzm3
The 10mm Spacer Dilemma
10mm wheel spacers are one of the most common spacer sizes out there. However, what a lot of people don't realize is that a 10mm size is not a true fitment on any BMW. It's considered a "tuner" fitment, meaning some extra thought is usually required to correctly install them. Only with the right combination of parts will a 10mm spacer fit without a vibration or other fitment issues.
Factory Hub Lips Are Greater Than 10mm
The depth of the lip on the car where the spacer will rest will vary. The available lip space may be 11mm and a 10mm spacer with its own hubcentric lip cannot physically fit. The spacer will bottom out on the lip instead of on the brake hat, leaving a gap between the spacer and the rotor hat. The biggest reason for this is the thickness of the rotor hat. The thickness varies by manufacturer and design. A thinner hat (such as used with aluminum Euro Floating rotors) will leave more lip protruding and make the problem worse. Most spacer manufacturers add an extra chamfer, or shoulder, to push the hubcentric lip further out. The extra chamfer clears any extra part of the stock lip. The other way to get the spacer to fit is to shave the stock lip with a metal file. While not the most elegant solution, it works.
Wheels With Incorrect Beveled Edge
Some wheels (Kosei in particular) have a beveled mounting surface that is at a different angle than on the spacer. Think of really precise puzzle pieces fitting together - if the pieces are not precisely machined to match, the parts don't fit together very well. The wheel will vibrate since enough of the wheel bore is not resting on the spacer lip.
Note that all of this only occurs when using a 10mm spacer with its own hubcentric lip. Any spacer over 10mm is not affected by this. The TMS 10mm spacers with Hub Extender
is also exempt from this as the spacer has a flush outer face and will not interfere with the mounting surface of the wheel.
What's the solution?
You could shave the stock lip on the car so its depth is under 10mm... Or you could just use a 12mm spacer and be done with it. The difference between a 10mm spacer and a 12mm spacer is the thickness of a nickel! The 2mm difference is smaller than the thickness of a CF memory card or your typical cardboard box. Trust us - 12mm is the way to go. The TMS Hub Extender/10mm Spacer set also works well and allows you to swap spacers in and out for different setups.
so is safe to use the 12MM spacers all around on a 09 ZCP oem wheels ??
thanks for the help