OldManMike

I too have been disappointed in the resonance noise heard on some roads. For my 2014 Audi A8 it is loudest at 75 mph on concrete roads. In an attempt to quantify the noise, I used a sound meter for the iphone called SPLnFFT:

https://itunes.apple.com/us/app/spln...355396114?mt=8

Here are the test results:

Audi A8 on concrete road interstate road:

Goodyear Eagle L2 tires All-Season (19 inch rims)
75 mph - Measured sound level was 70 dbA

My 12 year old Lexus LS-430 was 67 dbA


Another 2014 Audi A8L from the dealer’s lot:

Pirelli P Zero All Season (20 inch rims)
70 mph - Measured sound level was 72 dbA
(resonance occurred at 70 mph instead of 75 mph)


Audi A8 on a high quality asphalt road:

Goodyear Eagle L2
75 mph - Measured sound level was 62 dbA

And finally, sitting idle the car is a quiet 42 dbA

(Technical Note - 6 dB sound level increase is perceived as twice the loudness)

A spectrum analysis of the noise resonance shows that it is occurring around
215 Hz. This is a very annoying frequency for most people which is probably why there are many complaints about it.

As for the tires, they certainly can contribute to the noise level since an assembly with a pronounced resonance (such as struts or even the chassis) need a stimulus to start ringing. A possible Band-Aid for what appears to be a mechanical dampening design issue would be tires with much greater vibration isolation from the road. This tire seems to offer some hope:

Continental Tires Launches ContiSilent Quieter Performance Tire :: News :: autoviva.com

It would be interesting to have input from other Audi owners using the sound level measuring app to see the variation in data. I recommend taking the measurement with the iPhone at the driver’s ear level (but not against the head).

Mike

GR8-LIFE

took my car in to the dealer last week after a previous dealer blamed my left front rubbing noise (with 15K miles) on the tire. But after the rotation at 17K miles, I still heard the same noise. The noise did not move with the tire rotation. The 2nd dealer mechanic still blames it on the pirellis. He claims "Pirellies are known for this tire noise."

This is the first car I have ever owned where the tire is getting the blame. I don't think we have the same cause but we do share the same canned-like responses. He did say he would swap out tires from a newer A8 to prove to me it was the tire. This I have to see!

GR8-LIFE

when I discuss tire noise or wheel noise or any problem that I read on the forums with my AUDI shop the first response is "Don't listen to the forums" So I reply "R U Kidding? Ofcourse I have to listen to the forums. They own the same car as I do and are posting on issues I should know about. That would be like refusing to listen to patients who have all undergone a similar medical prodedure from the same surgeon

motegi

I think forums are an invaluable resource for this type of information. On the other hand I never tell the service advisor that I got my information from a forum. I usually just say that I learned it "from a friend".

Sharky10

Just fitted conti silents on my 13 s8, taking off conti sport contacts, in 275/35/21, both tires. The silents are not silent, but they are definitely an improvement.....I'll try to quantify it tomorrow, with my db meter.....my roads in oregon are pave with a very course finish, so I was getting a lot of tire noise before, which just ruins such a silent platform.....I can particularly tell at higher speeds, because now I can hear some wind noise, where before there was none....not a lot, tho...i need to take a ride in a lexus 600, and see if I'm willing to sacrifice performance for quiet....or spend more money buying smaller wheels with higher aspect all season tires.....maybe that would be quieter than the contisilents?

ffejrey

I'm back...

regarding the tire claim - I had Continentals Contisports originally. I have since purchased both the Goodyear Eagle Sport 275/40/20's and the Michelin PSS AS/3 255/45/20's. Noise exists will all tires. It is simply not a tire noise.

I am currently running the PSS's with a 28-29 cold tire pressure. This is the best solution I have tried thus far -- under-inflated skinny tires; how sad is that. The car is not quiet but it is more tolerable. New rubber being so soft also helped but after only 5000 miles on the Michelins, I can hear the humming getting louder again...

Audi knows more than they will tell. I too have had service advisors be very nice to my face... tell me they know of the problem, will follow up.. then don't and do not return my calls. It's almost like they want to tell us more but are forced by Audi mafia to shut their traps...

Like others first they told it was feathered tires. Then treadwear design and airflow patterns. After new tires I was then told (finally in writing) the noise is "the result of the wheels I have installed" - being the OEM wheels. How insulting can Audi be... A different dealership laughed at 20 inch wheels conclusion, said it was drive shaft related and rotated it 180 degrees. Since then I have even had a new drive shaft installed. Guess what... same problem...

I finally decided to try a sound dampening paint on all 3 of my front control arms 2 days ago - the product is called Noxudol :


It did nothing positive which is disappointing to say the least. I will post pictures of the install.

I now wonder more about driveshaft/axle/transmission resonance...

We need someone on the inside to help or someone who knows everything Audi... If anyone out there has any relationships with Audi or a great mechanic who specializes in them PPPPPPLLLLLLLLLEASE chime in.

If it were not for this issue Audi would have such a wonderful automobile... so sad.

I also found this other forum which is the closest I have found to anyone recognizing the issue:

Droning Noise [Archive] - VW AUDI Forum

A 8

I thought this was a good idea so got the app and used it while driving today. I am in Sweden and its just above freezing and wet roads (slightly more noise), its all asphalt roads but not very silent, they are made with large pebbles and most people drive with studded tyres which makes the surface rough. I've got my 18 inch winter wheels on, tyres are Michelin Pilot Sport PA4 235/55/18.

Standing still with engine on Idle, fan/ac off 39dBA, fan/ac on 45dBA
120km/h or 75mph I get between 63.5 and 66dBA.

There is however no specific peak level frequency, it constantly ranges up to around 400Hz.

Andoiwebb

Just a question for everyone suffering with this noise; when you press the brake pedal, does the noise reduce or change frequency? It does on my A8, it pretty much goes away.

I have some dynamat type material and will be fitting it to all suspension components and front bulkhead when the weather gets a bit warmer.

ffejrey

Thank you for the information. In the US, the only two tire sizes which are stock are 19 and 20 inch. I have driven my car with 19 inch wheels and the sound is substantially reduced; I am going to make the assumption 18 inch tires will even be more quiet... More rubber = softer ride = more absorption of friction.

This problem is not just a matter of decibels either, cars are supposed to make pleasant and proper noises… Not inconsistent and non-linear resonances. I also own a 2006 Subaru STi with no back seat and "hi-flow" cats... I love the sound of car - every aspect of it... Sometimes loud is even great in my world.

However in this vehicle, I will drive down the same stretch of freeway and have different responses and amplitude of the sound. The best analogy I can make again is running your fingers on the edge of a wine glass, or those Tibetan bowls - this is a resonance and undesired. Also if you hit a bump or joint in the road when resonance is occurring it increases in volume noticeably, and will even "donk" in the same frequency range. I have driven four Audi 8's (2011,2012,2014 and 2015) and all exhibit similar characteristics with an exact frequency - about 220Hz.

Please remember the composition of the road is a dominant factor. I believe this is because different road surfaces produce a different amount of friction/vibration in contact with the tire. I am certain this noise is not recognized as the same or by all owners because of this.

From my research, asphalt (and grooved asphalt) are the worst. Black top roadways (with more rubber) are quiet to almost silent. The road/tire is the input - but another component in the vehicle is the speaker. Audi is lying to everyone blaming the tire. Again I spoke with a sound tech engineer at Conti - different tires do not make the same noise and all tire noise is linear - it will not vary in amplitude at different times on the same road surface.

I would have MUCH more respect for Audi if they admitted this is a design characteristic of the car and were HONEST about what is the "speaker." This way the customer could make an informed decision, and potentially mitigate it. As it stands now we are being lied to by the brand we support and want to be loyal to. Bad move Audi... You will make less money and breed brand disloyalty because of this decision.

joeeluck

Hey everyone. I am a newbie to the forum. I just happened to be searching road noise on the 'Audi A8L' after a test drive and found this blog thread in my google search. We just took a 2015 A8L out for a test drive last night after having read many good things regarding the quality in the details, fit, and finish. If there was one thing I was expecting it was a very quiet ride. Now road surface withstanding, the vehicle was quiet in terms of wind noise....very very respectable. At freeway speeds 65-70, I was at odds with what I was hearing. At one point during the drive, I asked her if she could hear what sounded like a hollow sounding tone. I cannot recall her exact response, but I believe she agreed she was hearing something....more mesmerized by everything than listening to the different levels of sound as I was I surmise. I'll call it, wheel to chassis (unitized construction) noise harmonic feedback. There seems to be a issue with isolation between the road and the body of this car. I noticed it both around 40-50 mph and at freeway speeds. There was no considerable thought about this until I came home wondering many of the things I read in this forum, which led me to searching about it and finding this thread. With plenty of road miles of experience as many of you, I can undoubtedly note, this is not a tire issue. The drive wheels to suspension, to the Audi frame, noise isolation is lacking somewhere within some crucial components. I love the car, I am not impressed with surface road noise confinement. If this could be remedied this car could probably hold a title of one of the quietest. in 2015 at $100k+, I expect this type of engineering issue to have been long resolved.