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Why running 10mm spacers can cause issues.

Why running 10mm spacers can cause issues.

Spacer tolerances are so precise, that when designing 10mm spacers for BMWs, you have to choose between Backside Depth or Material Mass, and usually there is zero margin for error. Which is why Motorsport Hardware, and other reputable manufacturers, have disclaimers about the nuances of the 10mm hubcentric spacer. 10mm hubcentric spacers will always require extra care when using. The 10mm has to overcome 2 issues, 
1. Backside Depth: Having enough clearance to overcome OEM hubcentric hub/lip protrusion, which allows the spacer to sit flat to the hub.
2. Material Mass: Having enough material to hold the hubcetric spacer lip and still allow it sit flush to the back side of the wheel.
Most wheels have a large enough chamfer in the rear to allow the 10mm spacer to sit flat to the wheel hub, but there have been some instances of some older wheels not providing enough clearance.
10mm spacer
12mm spacer
The solution. The only full proof option is to run a 12mm spacer. They are designed with enough Material Mass on the front side so the hubcentric ring will clear the hub chamfer of all wheels and the Backside Depth has the clearance to overcome the OEM wheel hub/lip protrusion. 

Suggestions for minimizing issues:
  • Maintaining proper torque of the studs before the first on-track session with a quality torque wrench, that is stored correctly with the torque set to its lowest setting.
  • Recheck torque when the hardware is at ambient temperature. Do not torque hot hardware.
  • Wheel studs and nuts are wearable items so they do have a service life depending on the stress frequency. People who track heavily or race competitively should be replacing the studs each season.
  • For 10mm spacers, We advise checking torque more frequently.


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