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Light weight rotors, are they a myth

Posted: Mon Dec 19, 2016 9:55 pm
by geoffdunk
Hi all,

I keep seeing 20" original 20" ET26 rotors advertised stating they are the later special edition version that were 45% lighter than the ones used prior to 2015, is there in truth in this. The ones I have seen are RS5 wheels with 275 section tyres on but they are the same wheels as the RS4 with the correct dimensions.

I know my way round these cars pretty well but never knew about this, unless its BS of course.

I am after a 2nd set of wheels and want to make sure I'm not paying over the odds.

Cheers all in advance

Regards

Geoff

Re: Light weight rotors, are they a myth

Posted: Mon Dec 19, 2016 11:30 pm
by smudge
I have nothing much of value to add, other than with the weight of the car being what it is, I would have thought that a 20" wheel weighing some 45% less would be potentially weak also. I've not seen or heard anything though....

Re: Light weight rotors, are they a myth

Posted: Tue Dec 20, 2016 1:14 am
by geoffdunk
The theory is sound as reducing unsprung weight is always good, I just wasn't sure they existed, certainly not 45% reduction.

The wavey disks reduce unsprung weight by 4 kg.

Re: Light weight rotors, are they a myth

Posted: Tue Dec 20, 2016 1:54 am
by geoffdunk
smudge wrote:I have nothing much of value to add, other than with the weight of the car being what it is, I would have thought that a 20" wheel weighing some 45% less would be potentially weak also. I've not seen or heard anything though....
I'm gonna put a call into ex-colleges at Audi to find out.

Re: Light weight rotors, are they a myth

Posted: Tue Dec 20, 2016 3:02 pm
by Covkiller
This sounds like bullshit to me as not even forged alloys achieve a 40% weight saving over cast alloys

Re: Light weight rotors, are they a myth

Posted: Tue Dec 20, 2016 3:24 pm
by Surrey Sam
As above, I've got some BMW M-Performance forged alloys here and whilst lighter. They're not that significant a weight saving over the original spec items.

The 'edition' RS4 only had a different style of 20" rotor with the diamond cut or red outer lip - Order code PQV or PQ7. I think the lightest 20" wheels in the RS4 range were actually the V-Spokes?

Re: Light weight rotors, are they a myth

Posted: Tue Dec 20, 2016 3:41 pm
by geoffdunk
Covkiller wrote:This sounds like bullshit to me as not even forged alloys achieve a 40% weight saving over cast alloys
Exactly what I thought, thought I'd better ask around 1st though.