The reason I didn't mention that is because I haven't ran across any bad tires for years now. Last ones were in the mid 80s. A shifted belt in a tire can do the same thing. Thats why I asked if at low speeds like 5 Mph you had any side to side motion or simular things.
An out of round tire can do exactly what you have had going on all this time. I've seen it many times.

Good Luck... Hope this fixes it for you...

 

I have an 04 A6 and it has had vibration problems for over a year. The dealer put on new tires, balance the tires 5 times, staightened the rims, and it still is there. No solution yet. What a joke. I am thinking of buying new tires.

 

Well the tires seemed to fix the issue for awhile. The vibration will sometimes still appear and it drives me crazy but i'm learning to live with it although i def. expected better from my audi.

A vibration at idle has also appeared....i'm not sure if the two are related or not. I need to take it back to Audi to have them look at it again but having spent 4500 dollars on my audi already i'm outta spare cash as you could say.

 

Hey man, I cant remember if you have tried it already but I had weird vibrations at idle and between 45 - 60 mph. Sometimes it would vary and it seemed to come from all different places. But I replaced my whole center driveshaft (like 500.00 dollars) and that fixed every vibration I ever noticed. After looking at it, the bearings on each end were worn out (no way to tell until I had removed it) and my center support bearing was completly worn out (rubber bushing). If you havent I would inspect that. I heard its a pretty common occurence from the local Audi shop. Its above the exhaust and heat shield. The heat can destroy that center bushing or cause it to crack and you might not even notice it with a quick inspection, but even the smallest amount of play can give you crazy vibrations felt thru the peddle, transmission and even the tires. Let me know what you find if you havent checked it already.......

 

and I would also check all the supports for the differential, they were replaced on mine before I bought mine because of vibrations and drivability problems. Sorry, I cant remember everything you did already and I am too lazy to scroll back thru the post. If your anywhere in N. California I can help you check it out.....

 

haha i totally wish i was in northern cali but i'm on the complete opposite side of the US. I have not checked the differential mounts. I did check the motor mounts and they look brand new. The snub mount looks like crap. I also have had a engine vibration at idle now.

I had a mechanic check the driveshaft while the car was on a lift. He ran the car thinking that a joint was seizing in the driveshaft. He said he didn't see anything.

As soon as I get some money I'll have those looked at. I've spent more then 4000 dollars on this car and i've had it only 8 months. So i'm kinda outta cash.

 

yeah, I hate putting a ton of money into them. You end up hating the car. I bought mine with bent valves and had to basicly rebuild the engine, just to find out that my driveshaft was bad and I needed new brakes...... but now that I got those caught up, its an amazing car. Awesome in the snow and real comfortable. Anyways, I would make sure your timing belt is decent or new before going to far into too many other things. As for the vibration, its so hard to diagnose unless I could hear/experience it in person. Is there a weird sound coming from the gear shifter area at all around idle or when the power fluctuates when driving. I am still thinking its the centerline driveshaft, because that thing has more moving parts than you may think and if the bearings are bad at each end there is no way to tell unless you replace it. I had mine on a lift and I could see my center support bearing was crappy but I had no idea the bearings on each end were bad too. There was no play when I tried moving it on the lift. Thats the best thing I can think of unless the frame was bent in a wreck or something and no one ever told you about it......

Is it mainly from the front wheels or the back ones? Or all of them? If its just rear, it might be one of the gears in the rear differential....... but not likely.....

 

Thanks for the feedback. I'm kinda thinking that your right. Although the vibration is only coming from the rear/ center. I'm not getting any vibrations from the front of the car. This summer I will get it looked at when i'm having my rack and pinion replaced.

 

Ok so i took my car to audi again to have the issue looked at. They told me they checked everything: from every joint and any moving part in the drive shaft, to the mounts in the rear differential. The only thing that they could come up with was the wheels. Of course they would point their fingers at my wheels because they are after-market. I have hub-centric rings in them but I am thinking of going down that road again because they are a cheap option and I wondered if anyone had any of the same issues with after market wheels on their audi. Its almost like every single bump ( i'm not talking about noticeable bumps but bumps like uneven or slightly and I mean slightly rippled pavement send vibrations through the cabin). Low profile tires aren't helping either. I'm going to dig around some more and try my original wheels again and see what happens and also possibly order another set of hub-centric maybe from the manufacturer of the wheels.

 

I understand you have two different set of wheels. With your aftermarket wheels, if you swap them from front to rear, does the vibration differ? Does it feel different?

A local craiglist ad for same bolt pattern may also perform a cheap test. or a local audi meet.