[rzm3]

Miscellaneous Notes and Details on Spacers

• Most BMWs will take a 15-20mm spacer when used with the stock wheel/tire setup. This is because the German TUV (similar to our own DOT) still requires adequate clearance for snow chains. These are still widely used in Europe, especially in The Netherlands, Norway, and Sweden even though they are obsolete or irrelevant in other markets. The TUV also requires that every car in Germany be equipped with either dedicated snow tires or snow chains for winter driving.
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• All BMWs use hubcentric wheels. When mounted to the car, the wheel rests on a lip instead of the wheel bolts or studs. The lip is usually 9-10.5mm in depth. The lip contributes to the strength of the wheel and the wheel cannot safely be used without a lip. The wheel bolts are not strong enough to support the weight and loads generated through the wheel.
  
  Any spacer smaller than 10mm will not have a hubcentric lip on it. It's physically impossible since the spacer slides over the existing lip but is not thick enough to take the lip's place (the standard lip still protrudes through the spacer). With a 9mm lip, a 5mm spacer will only leave 4mm of stock lip left for the wheel to rest on. This is important to keep in mind when considering your wheel/spacer setup. A wheel with a beveled edge on the back will not adequately rest on the lip, resulting in a vibration because the wheel is not truly centered on the hub.
  
  For most 5-lug BMW applications, Turner Motorsport offers a hub-extender (link). This takes the place of your hub's dust cap and adds an extra 10mm of lip for the wheel to rest on. Using the example above, instead of 4mm left over on the lip, you now have 14mm of lip to use. With the hub extenders, you can also change spacers around without fear of losing lip space - it can be used with a 3mm, 5mm, 8mm, or 10mm spacer.
  
  Spacers with their own integrated hubcentric lip are: 10mm*, 12mm, 12.5mm, 15mm, 18mm, 20mm, 25mm, and 30mm.
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  * -- Note that H&R and Turner Motorsport each make a 10mm hubcentric spacer but due to interferences between the spacer and lip, it's best to leave this to specialized applications. The lip on the car must be shaved down so the 10mm spacer will fit flush on the rotor hat.
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• When talking about tire sizes, remember that sizes vary a great deal from one manufacturer to another. Even though the tire size is listed as "245", the actual widths can be hugely different among brands and even tire types. Tire manufacturers publish their actual widths on their websites. This is important because a setup with a wider 225 tire may rub versus a setup running a narrower 225 tire.
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• When installing spacers, never use anti-seize or grease between the spacer and the rotor hat face. In fact, you should scrub this area clean with Scotch-Brite or a wire wheel attachment. A thin amount of anti-seize can be placed on the lip of the hub for the spacer to sit on and on the spacer lip for the wheel to rest on. The number one reason for wheel vibrations with spacers is rust or some other substance on the rotor hat.
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• When installing spacers, never use anti-seize or grease between the spacer and the rotor hat face. In fact, you should scrub this area clean with Scotch-Brite or a wire wheel attachment. A thin amount of anti-seize can be placed on the lip of the hub for the spacer to sit on and on the spacer lip for the wheel to rest on. The number one reason for wheel vibrations with spacers is rust or some other substance on the rotor hat.