92pajero wrote:If anyone suggest loosening lug nuts and going for a short drive, loosening and dropping the jack and that sort do not understand how a rim really works in supporting the vehicles weight. The lug nuts only retain the rim onto the axle or hub, the center opening of the rim is coincidentally the exact size for the axle or hub. Reason being the rim supports the majority of the load on this, the lugs/lug nuts only keep the wheel tightly fixed to the hub/axle.
I can't disagree with this more. Once the lug nuts are properly tightened, the vertical load is supported by the friction between the wheel and the drum/disc. At least with clean/non- rusty parts.
If the fit were tight enough to support the load right on the hub, you wouldn't be able to get the wheel on or off. That the wheel goes on and off freely means that there is clearance between the hub and the wheel. Thus, in order for the hub to take load, the wheel would have to move relative to the hub, and it would have to be continuously moving as the wheel rotates. It wouldn't be long before friction would heat the metal enough to cause failure, or fatigue would snap your lugs.
The -centric suffix after "hub" or "lug" refers to the centering of the wheel on installation. With lug-centric wheels, you have to be diligent about incremental tightening to make sure the wheel centres properly. Hub-centric, you can be less careful. Once the wheel is tightened, it should not move relative to the hub regardless of the clearance at the hub.
Here's a good illustration:
http://www.miata.net/garage/hubcentric.html
The shiny bits on the disc are what is carrying the vertical and torsional wheel load. The lugs resist the side-to-side load from cornering (<-- gross simplification, as wheel offset, alignment, etc. will induce a bending load on the wheel even when stopped).