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I came across with this discussion about this topic, however it doesn't address the answer clearly.

What is the safety role of center hole (A) on the vehicle wheels? Is it supposed to carry the weight on the wheel and take the stress over from the wheel lugs?

Or, is it there only to help on assembly of the wheel?

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It depends on the design of the hub and wheel assembly.

Some wheel / hub assemblies use a controlled fit to locate the wheel central as the nuts do not have cones. This is usual for aluminium or alloy wheels as the cones of the lugs or nuts will compress and damage the soft metal of the wheel.

Steel wheels may not use the central register as the cones on the lug nuts and the wheels are designed to centralize the wheel on the hub.

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  • $\begingroup$ If the nuts do not have cones, then there are no parts that can hold the wheel in the center while driving (there is only a negligible (IMHO) friction between bolt heads and the rim's bolt hole faces). In this case a tightly fitted center hole will carry the wheel load. Is that true? $\endgroup$
    – ceremcem
    Jun 30 '19 at 8:57
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    $\begingroup$ If there was "negligible" friction between the bolt heads and the mating surfaces, The bolts would work loose in the first few miles of driving, and then shear off because of the alternating shear loads during every wheel revolution. But whether or not the center hole is a primary load path supporting the weight of the car, it acts as a secondary safety feature if some of the bolts fail. $\endgroup$
    – alephzero
    Jun 30 '19 at 9:02
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    $\begingroup$ There is the clamping force that is also designed to support the load otherwise the wheel will move continuously and work loose, and that is exactly how it is on my car. $\endgroup$
    – Solar Mike
    Jun 30 '19 at 9:02
  • $\begingroup$ That means that the center hole does not mean to support the wheel load in any circumstances except the fail safe case. (As the secondary safety feature is out of scope of this question, we can currently ignore that one) $\endgroup$
    – ceremcem
    Jun 30 '19 at 18:13
  • $\begingroup$ @alephzero The secondary safety feature would only work if the center hole (A) tightly fits to C (or B, if applicable), right? $\endgroup$
    – ceremcem
    Jun 30 '19 at 18:24

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