I experience a sort of rythmic vibration at high speed (90 plus). It's not in the steering wheel, it's through the whole car. I can't tell if it's just road feel or a wheel balance issue. Does anyone else experience this. Please don't admonish me for speeding, I'm only bad every once in a while.

 

What brand of tires?

How many miles on them?

When were they last balanced?

Any odd wear of the tread?

Sounds like something is up with the rear tires. I say rear because you don't feel it in the steering wheel.

 

I'd bet on rear wheel balance problems. I drive mine year-round and had an interesting experience a month ago - drove through slush, which ended up freezing inside wheels. Major vibration when I hit the highway but the ice broke off quickly and everything was fine.
Might also check if you just lost a balancing weight - it's generally pretty obvious where one was if it's gone.

 

Flat spotting. Do you drive the car routinely, or park it in excess of 10 days? Some tires are more prone to flat spotting over shorter periods of time than others.

 

I drive the car almost every day. I know the condition your talking about, it lasts only a few miles. I'm running Contis that have about half their life left. It's really not a very bad shake, wondering if the car is so sensitive to road that it's just picking up imperfections in the surface. I'm pretty new to the modern Porsche experience, it could just be the way they feel at speed.

 

No, it's the tires. Almost certainly. I went through the same phase with the set of tires on this car when we bought it. Like you, I wasn't familiar with modern Porsches and couldn't be sure, but it was the tires.

Gary

 

What I've been told can happen is the new tires are balanced. The car is used. The new tires become used tires, worn tires, but not yet worn out.

But the wear removes heavy spots (in the tread) and then the tire is out of balance.

Techs tell me this is real problem with Cayennes -- the tires are bigger -- but they've seen it with the tires on the cars too.

If the tires are properly inflated, showing no signs of damage, or odd wear -- feel the tire tread! -- then I'd think about having the tires rebalanced before throwing larger sums of money at the symptom.

Sincerely,

Macster.

 

Thanks, looks like I'll just fork over the eighty bucks for rear balance. I just hate it when they say " balance was good" but you pay anyway.

 

Are the tires simply old? You know, where the rubber simply isn't live anymore. I had a set of Continentals on a back up set of rims and they were the worst tires after they were aged.

 

the tires seem fine, don't appear old or in bad condition. The car was a CPO two months ago so I figured the balance or any other issues would have been addressed.

 

Bent wheel, perhaps?

 

hello - I see this is a really dated thread but I'm having the same exact problem and went through all the same steps you listed. The car is CPO 991 C2S. Were you able to find the cause of this problem and fix it? It gets very scary around 100+ mph.

Thanks!

 

You might need new tires. I have the same issue, problem went away after I got new tires.

 

Had the same and after 2 tries balancing did away with the vibrations.

 

I would recommend Road Force balancing the rear tires. I tried a brand new set of 4 Bridgestone S04 tires and they were so bad that the dealer could not balance them with their Road Force machine. I returned the set to TireRack. They were very professional and returned my payment very quickly. I replaced the tires with a slightly used set of Michelin Super Sports and they are as smooth as silk after Road Force balancing. It can be the tires or just balancing. Good luck!