Hello all,

today I was in a shopping center temperature drop down to 24 so I jump in the car, I started to drive slow and this sound "knocking" comes from my tires, sounds like If I had a flat tire and also feels the same when you turn your steering wheel, so I stop, walked around and everything looks normal.. could this be the tires? I'm running 21" F*** Pirellis..or maybe something with the suspension.. any of you guys that have a similar issue?

thanks

 

Hard to say without a lot more information. Pull the wheel off and have a good look at it inside and out as well as the suspension, brake system, axle, etc... Have someone else drive it forward while you walk along side to see if you can more specifically identify the sound and where it is coming from.

 

the sound was coming from the front, I feel it on the steering wheel.. if I was going to describe it, it was like having a flat tire, I inspected the car and nothing and then I started to think that probably it was a flat spot on the tires, I'm running Pirellis and this are the worst tires I think ..

 

If the car hasn't sat for an inordinate about of time (months at least but really these days it should take a year or more) or major skid (shouldn't happen if your ABS is working correctly) then I'd be shocked if you had a flat spot. Your OP also seems to indicate that it was fine going to the shopping center and then was messed up after.

Could be that you lost a weight from your wheel. That could feel like you describe and be a sudden change (wouldn't expect any noise though).

Does it go away with speed? If not, does it stay the same or speed up appropriately?

Do you have the air suspension or steel? If it's steel, do you actually feel anything other than in the steering wheel? If it was a tire/wheel issue I'd expect to feel it elsewhere too, though I'd also expect the air system to possibly hide such things from you.

Do you have Servtronic/Power Steering Plus? If this issue is only at low speeds (below 35mph if I remember correctly) that is when that feature is engaged. Could be a fault there.

We have a similar issue to what you describe in our 996. It only happens the first time it's driven on a day where the temp is 37 degrees or colder and only when backing up to the right. God awful grinding/rubbing sound and you can feel it in the steering wheel. It's been happening since it's first winter and the dealer never found a fix for it even after replacing the entire front end of the car (except for the body/frame). Hopefully yours is easier to find and solve.

 

thanks for the info, I stopped by the dealer today, I told my sales person about the issue he said that it was from the AWD shifting something related to that in order to not be dragging my tires

 

Don't talk to sales guys about technical problems and don't ask the techs about build options

You're AWD system should never make any sounds/vibrations unless there is a serious problem.

 

yes, you are absolutely right, thanks Gnat

 

I had a similar issue when our Cayenne was in below zero temps. Spoke to a Tech who said after driving the brakes still generate heat. After parking if any moisture comes between the pads and disc they could freeze at cold temps. His belief is that what we were sensing was the brake pads breaking free from the disc. Note we were driving thru fresh snow prior to parking.

 

Thats a good possibilty, that day was around -25f it was pretty cold

 

Why would you curse your Pirelli tires; especially if you are not sure they are the cause of your concern? They make reputable tires.

 

You are right, I was not sure, but they are the worst noisy tires ever, I had them on my 911 and my F-150

 

I second the Pirelli, I got the P zero before to put on my HRE for the BMW I had, supposedly the tires they put on Lamborghini from the factory, they were indeed the worst tires I've ever had..

super noisy, super stiff sidewalls.. then everything was stolen so it became someone else's problem

 

That is too funny.