RS6 feels bumpy after changing tyres

[Thilo]

2 weeks ago i got 2 new tyres in front and 2 nearly new tyres back. Since then my car feels bumpy. I brought the car 2 times to the tire guy and he always adjusted the tires new but still the same. The strange thing is, after driving 20 minutes, the problem is gone and it happens most of time when driving 100 km/ (60 m/ph). Is it possible that my DSC is broken or do i really have to put 4 new tires on ????

Thank in advance for your support.

Greeting from Switzerland

[DHall1]

Need more info

Is this a vibration on flat smooth roads?

If so, what tires did you buy and size?

[Thilo]

Hi Dave,

The tires i bought, old and new are Pirelli Z Rosso XL 255/40ZR18. It's exactly how you described it. I have havy vibrations on a perfect road (most roads in Switzerland are perfect) even the steering wheel is moving. I just talked to a guy from an other Audi garage and he said, it is necessary to have all 4 tires changed

The tire store balanced the tires now 3 times. I mean he is doing nothing else the whole day than chaning tires, he should know, that on a 4WD car he cannot change only two tires. He said, as they are on the same axle it doesn't matter. :eye:

I hope this info is usefull.

Greetings
Thilo

[vangelis]

I think you need to get it aligned at the dealer as they have a special tools for this there. I did it once and it was little bit expensive (almost $280USD).

[mballard73]

You may have a tire that is out of round but will still balance.

Check this site, I'm in no way associated with this company and there may be other balancing machines that do what this companies do. My brother told me about this as he and I both have other high performance cars we by tires for at times.

Check out the site and there information on Tire and wheel balancing.

http://www.hunter.com/pub/product/ba...159T/index.htm

Best Regards,

Mark

[mballard73]

I found this after I posted the one above, good info.

http://www.gsp9700.com/pub/technical/4202T/5THEO003.cfm

Mark

[Thilo]

Thanks for your feedback. What makes me curious is, that i have this car since 2003 and always went to the same garage and NEVER had any troubles. I don't believe that their equipment is bad.

There must be something else.

But anyway, i appreciate your input.

[mballard73]

It may just be the limitations of there equipment. All it takes is one bad tire or a slight bent rim for you to see this issue. I'm sure the shop you use is good.. but you do have a problem that sounds like a bad tire, not a bad suspension or DRC.

Just my take.

Mark

[Jani]

There can be a tyre problem, the tyre is just not round. No amount of balancing will fix that.

It can be a bent wheel. Same applies, since it is not round, balancing will not help.

Both these issues can be checked visually when the wheel is in the balancing machine.

It can be something with wheel bearing or some other suspension component as well, but first the tyres and wheels should be checked for roundness.

[mmaturo]

There can be a tyre problem, the tyre is just not round. No amount of balancing will fix that.

It can be a bent wheel. Same applies, since it is not round, balancing will not help.

Both these issues can be checked visually when the wheel is in the balancing machine.

It can be something with wheel bearing or some other suspension component as well, but first the tyres and wheels should be checked for roundness.

Agree ^^^^ I have had the exact same issue 2 sets of tires ago that did indeed take three trips to get the balance of one particular tire right. I haven't had an issue before or since.

[Hy Octane]

What tire pressure are you using? This sounds like what happens if you dont have enough air pressure and the car sits overnight.. if they are underinflated they go flat on the bottom overnight and then take a few minutes to re-round after driving. Check your pressures.

[BLITZEN]

since it didn't shake before, it can't be a bent wheel unless it was bent in the tire change process.

Most likely it's an out-of-balance tire. I've had new tires balanced and still felt vibrations at certain speeds, then gone to another tire shop and found that their balancer showed one or two tires out of balance. It can be tricky.

[DHall1]

A couple of things.

1. How "old" are the tires? Get the date code of the tires.
2. You may have a defective tire or tires. Spin each one on the balance machine and watch it spin. If its out of round it will hop as it spins. Your tire guys should know this. Shame on them

Hi Dave,

The tires i bought, old and new are Pirelli Z Rosso XL 255/40ZR18. It's exactly how you described it. I have havy vibrations on a perfect road (most roads in Switzerland are perfect) even the steering wheel is moving. I just talked to a guy from an other Audi garage and he said, it is necessary to have all 4 tires changed

The tire store balanced the tires now 3 times. I mean he is doing nothing else the whole day than chaning tires, he should know, that on a 4WD car he cannot change only two tires. He said, as they are on the same axle it doesn't matter. :eye:

I hope this info is usefull.

Greetings
Thilo

[V8weight]

What if the tire tech cranked the wheel down incorrectly and screwed up your hub centric ring?

[DonS]

I've been through this as well. Spin the rim alone, and the tire mounted in the rim on the balancing machine and watch for any lumps or bumps. You probably have a bad tire as the rim was good before. Heat can smooth them out, but usually these problems are speed sensitive. Modern tires rarely stiffen much over night and quickly soften under heat and load (my 911 tires soften out the flat-spots after 5-10 minutes of driving after being stored for months). I suspect you'll find the problem with one of the used ones, but you could find a rare new tire defect! You are not searching for a needle in a haystack, just up to 8 problems (probably only 1) with 8 componants (4 tires, 4 rims). Good luck!!

What is the history on the used tires?

[Skaala]

I just changed to Pirelli P Zero on the RS2 and Pirelli P Zero Rosso on the Q7. First couple of days felt very bumpy....but is has now disappeared. First time I try assymetric tires, where the rolling direction is not mentioned, only "inside" and "outside" It looks a bit weird, and I have never tested tires that felt bumpy before when new.....but I was assured by the tire dealer that it was normal in the running in period. I use 225/40/18 on the RS2 and 295/35/21 on the Q7.