I'm not an expert but I believe what you are asking is what ultimate tensile strength the wheel has; ie how brittle it is compared to aluminium. The answer...

http://en.wikipedia.org/wiki/Ultimate_tensile_strength
4137 MPa for raw carbon fiber and 1600 MPa for carbon fiber laminates; it does not deform/yield before failing. A aerospace grade forged aluminium alloy (2014-T6) fails at 483 MPa and deforms at 414 MPa. You will even shear titanium before you shear carbon fibre (and yes, why would a "industry leader in carbon fibre" like Pagani, unlike everyone else in aerospace and racing, use titanium in a carbon fibre weave when the carbon fibre strands are 2-4x stronger? Good question! We know why F1 teams use aluminium honeycomb and it's because the honeycomb unlike stretched titanium strands have the ability to flex and deform so the sum is greater than it's weak parts. Carbotanium does sound cool though, it's just too bad you can't find any scientific material that will support it's use! ).


The second question is "why do some carbon fibre wheels fail then?" One, a CF wheel failure will still make a huge impact in the social medias while forged aluminium failures are rarely mentioned even though they are far more common. And two, most of the earlier ones, like Dymag which Koenigsegg used for a period, had centers made out of magnesium that are even slightly weaker than aluminium which has given CF wheels a bad rep. Dymag then switched to Magnalium which is a magnesium/alumium hybrid that brings it closer to forged aluminium but still not anywhere near as strong as a properly made CF wheel that is both stronger in the material itself and has no weak spots where the center attaches to the barrel (I've seen a couple where all the spokes have been pulled clean out of the barrel).

This is your typical failure in those hybrid wheels: as you can see the center fails long before the CF barrel...



(fatigue)



(impact)



(Koenigsegg CCX's custom Dymags, with 11 spokes instead of 9)

So there you have it. They "could" fail but as seen in the hybrid CF/magnesium wheels the CF is not the weak spot by any stretch of the imagination.


This video shows how thoroughly over engineered the Aircore wheels are. The barrel is just as massive as the old Dymags but the center with the CF spokes is just absurdly overbuilt...

 

Extremely interesting thank you for everything contributed.

I have to say that I am now extremely curious as to why Ferrari, Mclaren and Pagani are not using CF wheels.

 

Im sure they will in very short time

 

Do you not think they would have done it on their latest hypercars as that would seem to be the logical place to introduce a product such as this. If the advantages are as you state then surely cars of the like of the P1 and LF would be best able to exploit the advantages.

I'm sure I'm missing something here, just not sure what it is

 

Frankly I'm more surprised that the CF wheels are not an option in the Huayra (as CF seems a bit more up Horatios street of glitzy "kitsch"). You'll have to forgive my skepticism but I think that something must be afoot.

 

Very true mate. The problem I have with carbon and wheels is that when it does fail it does not do so gradually, i.e. it does not bend. When it breaks it really breaks.

Ok here is another question. Today’s carbon brakes can operate at really high temperatures. How will carbon wheels cope with the heat soak from carbon or steel breaks after a few laps on a track?

Again I have never seen any racing cars using carbon wheels, Why??

If they are as good a reported surely racers would be using them as the weight advantages would be very beneficial

 

I agree with the bolded comment entirely. I would be a bit wary as the owner would likely be oblivious to a potential catastrophic incident until it finally occurred whereas aluminium wheels would surely give a bit of a warning before they had taken one too many knocks.

Time will tell whether this is an unsafe gimmick or an extremely useful innovation.

 

Great reading, thanks. A buddy just picked up a silver CCX here in SoCal.

 

So Hennessey just broke the Production Car Top Speed Record (I thought the Veyron SS had it, but the reasoning as to why that record didnt count is sound) at 265.7 mph. Reaction? Any plans to beat it?

 

"production car" sorry i cant call something that is registred as a lotus a car of its own. Its just a modified lotus on paper.

Fastest accelerating Real Production car = agera r
Fastest Production car top speed = Veyron SS