What Supports Wheel Load?

[SubLGT]

If you have an aftermarket wheel with a plastic centering ring (for a hub centric application) and the mounting holes (stud holes) have conical seats, what supports the lateral load on the wheel? I have read that the friction between the wheel and hub supports the load. I have also read this is incorrect, and the hub studs (lugs) are what support the lateral load.

"...Fact is, the hub centric rings do not bear a load. The weight of the vehicle is actually supported by the friction between the wheel and its mounting surface on the axle. The friction is established and maintained once the lug hardware is properly installed and torqued to specs…"

http://www.onallcylinders.com/2016/07/28/hub-centric-hubbub-argument-using-hub-centric-rings-wheels/

 

[gaijinnv]

Yes

 

[andyd]

Many hubs have a flange that could support a wheel and 1/4 of the car. Are you saying this is just for centering on the lugs?

 

[Colt45ws]

If the lugs had to support the load, they would snap pretty quickly. Try running with loose lug nuts and the stud will snap.
A 1/2" lug stud tightened to about 100ft.lbs. puts 12k lbs of tension on the wheel. Times 5 studs and you get 60k lbs holding the wheel to the hub.

 

[eljefino]

Since I usually have to hammer wheels off the hubs, even lugcentric ones, after a few months, I, too am convinced that the mating surface is a pretty good connection.

It may not be the only one, but it's a good one.

 

[supton]

Originally Posted By: Colt45ws
If the lugs had to support the load, they would snap pretty quickly. Try running with loose lug nuts and the stud will snap.
A 1/2" lug stud tightened to about 100ft.lbs. puts 12k lbs of tension on the wheel. Times 5 studs and you get 60k lbs holding the wheel to the hub.
I'm not entire sure I agree: I've loosed up lugs and driven on the wheel in an attempt to break loose a stuck rim. I think they were all hub centric... but still, the side forces on the lugs would still be there.

Granted this was short distance! but hard cornering just the same. Are you saying they'd snap in short time? If so, I could buy that.

 

[Quattro Pete]

Originally Posted By: andyd
Are you saying this is just for centering on the lugs?

Yes.

 

[MolaKule]

The high coefficient of friction of the hub-to-wheel connection is what supports vertical loads.

The lug nuts are there to keep that coefficient of friction connection high and to resist any lateral loads. Lugs nuts are in a high tension situation.

 

[CR94]

Originally Posted By: MolaKule
The high coefficient of friction of the hub-to-wheel connection is what supports vertical loads. ...
Not exactly the coefficient of friction, but the product of the coefficient of friction times the high force (due to lug nuts) between hub and wheel.

 

[SwampSurvivor]

Originally Posted By: MolaKule
The high coefficient of friction of the hub-to-wheel connection is what supports vertical loads.

The lug nuts are there to keep that coefficient of friction connection high and to resist any lateral loads. Lugs nuts are in a high tension situation.


I agree with this. I couldn't figure out how to word it though.

 

[SubLGT]

Originally Posted By: MolaKule
The high coefficient of friction of the hub-to-wheel connection is what supports vertical loads...


Would a thin coat of anti-seize between the wheel and hub reduce the coefficient of friction? If so, it seems to me we should increase the torque on the lug nuts to compensate.

 

[Colt45ws]

If you anti-seize the studs as well, that will increase the tension.
Bringing back the example 1/2" stud the tension would be 15,000 lbs instead of 12,000. Still at 100ftlbs.

 

[supton]

Originally Posted By: SubLGT
Originally Posted By: MolaKule
The high coefficient of friction of the hub-to-wheel connection is what supports vertical loads...


Would a thin coat of anti-seize between the wheel and hub reduce the coefficient of friction? If so, it seems to me we should increase the torque on the lug nuts to compensate.


I'd think so, although on the steelies on my two vehicles, I've noticed that the points of contact almost never have the antisieze left in place at rotation time. I think there is enough flex to clean those areas. I'll have to take pics next time I do a rotation.

 

[jiho]

The bearings carry the load. That's why they're called "bearings."

Torquing the lug nuts creates clamping force between the two mounting surfaces. Clamping force transfers the load to the bearings. The combined clamping force of several lug nuts is very large when torqued to spec.

There is no such thing as "hub centric" or "lug centric." Hub shapes and plastic rings help in getting the wheel into position to line up the lugs for easier torquing of the nuts, and that's all. If the wheel isn't positioned correctly or the nuts aren't torqued, then you get loading in the wrong place and things get nasty.

 

[HangFire]

Originally Posted By: jiho
The bearings carry the load. That's why they're called "bearings."


One of the first things you learn in Engineering Statics is that a single load can be born, in full, by multiple components of a system.

It's not hard to understand. If you're an acrobat at the bottom of a pyramid, all the weight on your back is also on your hands and knees... plus your own.

 

[jiho]

HangFire --

True to an extent, but for the point of this discussion it's the bearings.

There's no load on the hub. The load on the lugs is from torquing them, not from the weight of the vehicle. There's no load on the surfaces the lugs clamp, because they have been clamped to the point where there is at most microscopic movement between them.

It's the bearings that take the heat.

 

[jiho]

P.S. -- That's why they call them *wheel* bearings.

 

[CapriRacer]

As a thought experiment, imagine what would happen if the wheel were to experience an increasing load - AND - the hub that it is bolted to were rigid and unyielding. I would imagine at some point the clamping action could be overcome and the wheel would move relative to the hub and the lugs would stretch.

What if I compared a properly torqued wheel with one that was only torqued to - say - 10% of the proper value? Would the load on the wheel where it shifted be lower? I would think so.

So while the wheel bearings do indeed support the load, the wheel lugs are an important link in the chain and must be adequate to the job.

 

[jiho]

Absolutely true.

 

[HangFire]

I tried.