Originally posted by TourDeForce:
The hub carries the weight of the car.




No! The friction between the rotor hat and the wheel face hold the weight. Under extreme conditions, especially if the metal surfaces in contact are greasy/dirty/rusted, there is a small amount of movement. This causes fretting of the surfaces, and fatigue wear on the lugs. This is one reason to use HC rings: they help reduce this motion. The other is that they make it much easier to mount the wheel.

Also, think about this: when I decelerate at nearly 1G, I'm transmitting a huge amount of force RADIALLY through the wheel/hub/hat interface. It's sure not going through the hub, since it's a radial force, and it can't be going through the lugs or they'd break: it's being borne by the friction force that also holds the weight of the car.

-Philip Maynard '95 Contour [71 STS | Track Whore] '97 Miata [71 ES | Boulevard Pimp] 2006 autocross results