I drive a 2019 991 TTS with the center lock wheels and Pirelli tires. I live in NYC and keep it in an indoor garage here in the city. It has 5100 miles on it and just about 2 years old since I bought it new

problem I have is when I make a somewhat tight turn at slow speeds the front tires slip and it feels strange. I examined the tires and it does have a somewhat flat spots since it is driven once per month and parked. Should this slip be happening? Do I need new tires? Tire rot?

thank you

 

Too cold for your summer tires.

 

Pirelli tires and slow speed with lots of steering input definitely make weird noise and sensation. Search on acorn effect. Drive the car more.

 

Its normal in garages. Mine is only RWD and it does it. It does fee weird. Its just the tyre slipping on a tight turn. You shouldn't have flat spots on your tyres unless you lock up the brakes frequently, or your ne of those people that turn a cars steering wheel without moving. You always should move ever so slightly at a minimum when turning a wheel. Not be stationary and wind on full lock.

The slipping in underground car parks, completely normal. I hate it as well.

 

Ha yes that’s what it is; though today was 46 out and not that cold all considering. I guess since I am moving it to San Diego that will/may go away with the warmer weather

thank You

 

best not to turn too sharp..gets worse in cold weather w Pirellis,,i make wide turns now

 

Yup. If you have decent summer tires, they will pop like crazy in the cold, specially starting out backwards or forward with the steering cut hard.

The magic number is 40 degrees. Some manufacturers even say that you shouldn't even let the car SIT in 40 degree weather. That's pretty extreme.

I have taken mine out in 35 degree weather just to see how bad it is under braking and I get a LOT of ABS action. If you are in winter country. you want to drive your car when the roads are good so it doesn't just sit there, but remember that it may not stop when some idiot does something.

For day to day, find something else to drive in the winter!

 

Ackermann effect posts and cold temps, peas in a pod.

 

^ This.

I'm a member of SAE, and the association has several technical papers available on Ackermann Steering Geometry, including this one: https://www.sae.org/publications/tec.../2006-01-3638/

 

Yep, I recall reading about this very thing and even seeing videos about it before purchasing my 991.2. Then it happened to me and all the knowing and foresight couldn’t eliminate how strange it feels. But, it is what it is. Happens when the tires are cold. And it doesn’t have to be in the 30s or 40s. Has happened to me on a South Florida morning in the 70s. Eventually, you just get used to it but it will always make you wince a bit when it happens.

 

Yes almost feels like the wheel is falling off or steering axle is loose

 

You are experiencing Ackermann judder:

 

Man am I glad I came across this thread. I’ve experienced the same judder in a new to me 18 Carrera S and was scared the rear axle steering system is bad.

It’s a pretty disconcerting sensation that I’ve never felt prior with many 911s.

 

Acorns

 

Just weighing in to say that I feel this too. The shape of my driveway makes it impossible to avoid a sharp low speed reverse steering cut. So I feel this every time I back out. It’s certainly disconcerting.