20" wheels on your S8?
10-05-2020, 05:19 AM
#11
AudiWorld Senior Member
Thread Starter
Thank you VentsiBeast; that seems to be the consensus (talking to a person vs scrolling the internet). What tire size did you go with, both for the OEM and the BBS XA?
MP; the wheels I'm looking at (along with tires) comes out to 28.7", both for 20" and 22" applications, while my setup is 28.3" currently. I fully understand the concerns behind unsprung weight and realize that going to a bigger, wider wheel will definitely make an impact, I've no intentions of taking her on the track. The 22" rims I'm considering came off Fez' 2013 A8. I figured if they fit his car, should fit mine, larger rotor and brake setup notwithstanding.
The idea of autocross in such a large sedan isn't the draw it once was; I'm perfectly fine with driving more or less sedately with the occasional white-knuckle surprise when flooring it. That never gets old!
MP; the wheels I'm looking at (along with tires) comes out to 28.7", both for 20" and 22" applications, while my setup is 28.3" currently. I fully understand the concerns behind unsprung weight and realize that going to a bigger, wider wheel will definitely make an impact, I've no intentions of taking her on the track. The 22" rims I'm considering came off Fez' 2013 A8. I figured if they fit his car, should fit mine, larger rotor and brake setup notwithstanding.
The idea of autocross in such a large sedan isn't the draw it once was; I'm perfectly fine with driving more or less sedately with the occasional white-knuckle surprise when flooring it. That never gets old!
10-05-2020, 08:43 AM
#12
AudiWorld Junior Member
I just bought a set of Alutec 19x8.5 wheels from Tirerack for my winter use on 2016 S8 plus with ceramic brakes. They fit perfectly. I would think you shouldn’t have any problem with 20’s.
10-05-2020, 11:26 AM
#13
AudiWorld Senior Member
Thread Starter
Thanks sleepdoc; as was noted, it all depends on the offset and the variations in the spokes of the wheels themselves. Vossen, per VentsiBeast, is on record stating none of their 20s fit their in-house S8. Disappointing, but not unexpected. Rohana told me the same. Awaiting word back from Blaque Diamond and Niche, among others. May make the jump to 22's, but am hopeful I might find a set of 20s, otherwise I will.
10-06-2020, 09:14 AM
#14
AudiWorld Member
The Vossen models that I had my eye on would not fit. Vossen themselves recommended 2 or 3 different models in 20 inch that would fit, but I didn't like their design. For the models that I initially wanted, they said I must take 21 at least.
Tried to find my emails but I guess I've deleted them. My point was that you can't say "My car came with 20s so all other 20s would fit", because some just won't, even if the offset and everything else is the same.
Regarding your question about size, I assume you mean width? I don't remember the width of the BBS but I do remember they are 0.5 inches wider than the stock. So if the stock 20s are 9.0J, the BBS I got are 9.5J. Offset was the same as stock (I think). The car's stance is well-improved, as the wheels sit a little bit more to the outside, but it's very noticeable and looks way better. So far I haven't experienced any drawbacks and the only practical difference is that with the slightly wider stance the steering wheel feels a bit heavier. I personally don't like very light steering, so for me this is fine.
10-06-2020, 09:28 AM
#15
AudiWorld Super User
It isn't just track or race; that informs some for folks who have thought about it more for outright win or lose. This weight is unsprung and rotating, the absolute worst on a vehicle. Rules of thumb for rotating mass are 2-5 x static weight, so 40 or 50 pounds rotating could be up to 250 static; that a lot. 10 or 15 more pounds unsprung per corner ten of thousands of cycles is that much more a beating on a suspension that many recognize as a continuing D body weak spot durability wise. The original design is mid 90's A4. The weight of the complete wheel including tire for an old A4 could be as little as half a 22 even with no tire. Bigger brake set up needs--also unsprung and with rotor rotating--for all the pork (and power) has worsened it. Part of why Audi sprang for the pricier quasi two piece brake rotors.
Mass slows down acceleration, increases braking distance and hits fuel economy and range. Street or track. The fuel economy point gets buried in required Euro C02 disclosures, but it is there even for 20-21 step, specifically for D4's. I posted info in past on that. Tesla EV data is telling too, where range drops as wheel sizes go heavier. And/or wider for Cd. Same on etron IIRC. Never gonna hypermile an S8, but there are real world consequences at the margin.
Last edited by MP4.2+6.0; 10-06-2020 at 10:18 AM.
10-10-2020, 08:51 AM
#16
AudiWorld Member
I think the weight point may not be clear.
It isn't just track or race; that informs some for folks who have thought about it more for outright win or lose. This weight is unsprung and rotating, the absolute worst on a vehicle. Rules of thumb for rotating mass are 2-5 x static weight, so 40 or 50 pounds rotating could be up to 250 static; that a lot. 10 or 15 more pounds unsprung per corner ten of thousands of cycles is that much more a beating on a suspension that many recognize as a continuing D body weak spot durability wise. The original design is mid 90's A4. The weight of the complete wheel including tire for an old A4 could be as little as half a 22 even with no tire. Bigger brake set up needs--also unsprung and with rotor rotating--for all the pork (and power) has worsened it. Part of why Audi sprang for the pricier quasi two piece brake rotors.
Mass slows down acceleration, increases braking distance and hits fuel economy and range. Street or track. The fuel economy point gets buried in required Euro C02 disclosures, but it is there even for 20-21 step, specifically for D4's. I posted info in past on that. Tesla EV data is telling too, where range drops as wheel sizes go heavier. And/or wider for Cd. Same on etron IIRC. Never gonna hypermile an S8, but there are real world consequences at the margin.
It isn't just track or race; that informs some for folks who have thought about it more for outright win or lose. This weight is unsprung and rotating, the absolute worst on a vehicle. Rules of thumb for rotating mass are 2-5 x static weight, so 40 or 50 pounds rotating could be up to 250 static; that a lot. 10 or 15 more pounds unsprung per corner ten of thousands of cycles is that much more a beating on a suspension that many recognize as a continuing D body weak spot durability wise. The original design is mid 90's A4. The weight of the complete wheel including tire for an old A4 could be as little as half a 22 even with no tire. Bigger brake set up needs--also unsprung and with rotor rotating--for all the pork (and power) has worsened it. Part of why Audi sprang for the pricier quasi two piece brake rotors.
Mass slows down acceleration, increases braking distance and hits fuel economy and range. Street or track. The fuel economy point gets buried in required Euro C02 disclosures, but it is there even for 20-21 step, specifically for D4's. I posted info in past on that. Tesla EV data is telling too, where range drops as wheel sizes go heavier. And/or wider for Cd. Same on etron IIRC. Never gonna hypermile an S8, but there are real world consequences at the margin.
"Although Tesla is more forthcoming than most automakers about providing range figures for the various wheel-and-tire combinations it offers—it is only required to report the most popular option—it does keep the occasional tidbit to itself. For example, based on the road-load data it has submitted to the EPA, opting for 21-inch wheels on a Model S Long Range Plus will cut the range by nearly 80 miles. You won't find that information on Tesla's website. "
10-15-2020, 03:50 PM
#18
AudiWorld Senior Member
Thread Starter
MP or anyone, what is the weight of the OEM 21" wheels, is there somewhere I can find info? I suppose I could pull a wheel off but without a scale it would be a waste of effort. Also, none of the aftermarket wheel sites I've been ogling seem to have this information. Never considered unsprung weight or rotational force before.
10-15-2020, 06:30 PM
#19
AudiWorld Super User
See my reply #7 here, where I ultimately personally weighed it at 35.4 pounds: https://www.audiworld.com/forums/a8-...wheel-2897889/ That is, wheel only, 21 x 9, 5 spoker fitted on 2015 USA S8. Variety of other OE wheel info in same thread for a deeper dive.
This page says approx 16 kg., which is approx 35-¼ pounds. https://www.original-felgen.com/4h0601025at1h7.html Ties off closely to my own measurement.
This page says approx 16 kg., which is approx 35-¼ pounds. https://www.original-felgen.com/4h0601025at1h7.html Ties off closely to my own measurement.