Radiation Joe

Several people have posted statements that the RS4 wheels are not rated for the load of the RS6. I just made some statements on the RS6-dot-com site to the contrary.

Am I out in left field on this one? Does anyone have documentation of wheel load ratings for the RS4 and RS6? I think these statements are an extension of the tire load rating discussions about XL rated tires and not applicable to wheel loads.

I don't want to spread mis-information, so if anyone can show me why an RS4 wheel cannot be used on an RS6 due to weight concerns, I'd like to see it. I will imediately retract my RS6-dot-com statements.<ul><li><a href="http://www.rs6.com/forum/showthread.php?p=93625&amp;posted=1#post93625">My urban legend rant ...</a></li></ul>

rlsrls

I have a set on my car and I am not real worried about it. It made no sense to me either.

Hy Octane

has provided us with info no-one else was able to obtain, and he has been right 100% on everything he has said so far. When this topic first came up, he was the one to point out that the RS4 wheels were not rated to handle the extra weight of the RS6. he did not list numbers to back it up but he dosent post if its not accurate info.

néné

I use 20lb wheels for Summer in 19", and 22lb wheels for Winter also in 19", and have no idea what this wheel load rating is all about.
The only issue I've had in 2 years with the wheels is that the wife forgets what size the beast is in comparison to her cars, and somehow the rear wheels always find curb.

Curb rash on the Winters is ok though. Just gives me more excuses to keep getting new wheels.

One thing I love about the lighter wheels is that they make the car steer so much better!!!!

RS6-4dr911

Appears to me you could both be right in your own contexts. From a practical standpoint, how many of us (% wise) are really stressing the cars to even 80% of design load EVER, much less on a daily basis? So, in the real world, a change of capability is not a limiting factor. So enjoy the wheels on the street, they look great. On the track on a regular basis, however.....

Ever seen a broken wheel? I have, it happens, nothing funny about it when it does. So clearly there are some significant loads on wheels during track driving. And if you have a lighter wheel (superior design analysis and/or material of construction, i.e. Unobtanium, not withstanding) the material to lighten the wheel went somewhere and took some strength with it, and maybe the manufacturer shares some of that lost cost with you - or maybe he buys more insurance with the savings.

Secondly, tire loads and wheel loads are of course related since the wheel is what connects the tire to the car and all of its weight, therefore it is not IN the load path, it IS THE load path and as such both are subject to weight limitations. Depending on how each is designed they could be the same but most likely one is higher than the other, who knows which for a given tire-wheel combo.

Finally, for design load think Nurburgring for hours on end (like the new RS6 vid's circulating the net) That is severe loading and I can see a few hundred pounds (5%) making a difference. What I think is being overlooked here is that wheel loading is severe in a corner, and it is not a "static load" it is actually a cyclic load, going from a compressive load to a tensile load with each revolution which creates a fatigue environment - that's bad. Allowable stresses drop dramatically when designing for fatigue instead of just static, or dead, load. Add to that the increased heat coming from the tire, the wheel bearings into the hub and especially the searing heat from the brake rotors, and the strength of aluminum falls way off.

So Dieter, or whatever the GmbH mole/expert's name is, is most likely correct. And if you plan to track the car for more than a day or two, I would be inclined to heed well his advice. If, however, you use the car the way 95% of owners do (frequent straight line blasts and occasionally going at 8/10's through your favorite set of curves) I would say - Enjoy the looks and admiring glances - cautiously.

There, I have spoken. My college professors would be proud I still remember that kind of crap.

skiwi

but it would be easy to check with the manufacturer. simply ask whether the wheel is rated for the vehicle and get them to certify it.

one issue that might be obscuring things is the (reported) differing offsets of the wheels. if true, this would add wheel bearing loads into the mix...

Radiation Joe

There is no situation where a person could break an RS4 wheel where they wouldn't be so far into the probability of breaking an RS6 wheel that it could possibly make any difference.
You understand that there is no reasonable weight value above which the the wheel is expected to break? Right? It becomes a question of probability. The probabilities are a function of all the bad things that have been done to the wheel (eg potholes, curbs, gator bumps on the track). If an RS4 wheel was broken after being used on an RS6, there is a reasonable probability that the stock RS6 wheel would have broken at that time or even before the RS4 wheel under the same circumstances. The probability of a suspension component failing catastrophically is just as likely as one of these hugely over engineered factory wheels.

skiwi

don't forget that audi endured a lot of bad press due to the b5 rs4's propensity to *bend* rims.

Squirrel

Metallurgy and Materials Lehigh University.

Radiation Joe

I got my engineering materials degree from San Jose State University. Never really used the degree other than some corrosion work in the nuclear field.
I'm going to drop the subject now. All I'm doing is polarizing people to me and besides, maybe I can get a better deal on RS4 wheels if others think they are inferior to stock.

Joe