^this

 

 

Maybe a silly question STG, but the facts don't add. Can you confirm your "corner" is a left hander vs right?

 

I'm not the OP here. Just an observer

 

Looks like it was driven flat maybe with tire on 1/3 of the wheel. Looks like Big chunks of paint probably came off when new tire was mounted

 

Makes sense. Someone got a flat and drove on it while wheel got chewed up. Damage looks consistent with that. Can happen pretty fast if it lost pressure fast. Previous damage I'm saying.

 

I agree with STG. Looks like older damage. I would also think if you rolled a tire, which is highly unlikely if the driving was as you mentioned, that significantly there is a good chance you would have broken the seal to the rim and blew the tire out. The damage is almost 80% of the circumference of the tire. With a roll and you basically riding on the road I would also expect the damage to be greater. This looks older and I couldn't even guess the cause on a loaner vehicle.

 

It just happens that whatever noise you heard, you associated it with the back wheel which happened to have pre-existing damage. I wouldn't worry about it.

 

The noise you heard may have been the PSM.

 

Looks like perhaps it had been repaired previously and the old new paint is coming off. I would just turn it in and not say anything as the evidence would not suggest you hit anything.

 

That's what I was thinking as well, the damage looks old. That flaking of the paint is bazaar as well. I've never seen anything like that before. Personally I'd just turn the car in and don't say anything about it.

 

While I appreciate the input and ideas about possible causes and next steps, I should clarify a couple of things further:
1. This is a rental car from a major rental car company. I've had it for a few days. When I picked it up we did the walk around and carefully noted all existing damage. I looked carefully at the wheels because I know these are particularly prone to damage with the low profile tires. I observed no damage. The rental car guy actually found stuff on the underside of the front spoiler that I didn't spot and called my attention to it. Bottom line: there was no pre-existing rash on this wheel.
2. As soon as I got into my garage I checked the tire pressure and got a 40 psi reading, which was one pound higher than this morning, when I checked it again cold. The reason the difference wasn't that great is because I only drove the car about a mile down the road to pickup takeout food.
3. At the bottom of the first picture I posted you can see a bit of silver-colored material on the sidewall of the tire. Someone posted a comment asking what that was, so I went out and looked again, it was actually a paint chip that came off as I was cleaning up the wheel with a damp paper towel before I took the picture.
4. In the pics below, note the arrows pointing to the mold marks on the left tire, and their absence on the right tire. Even though the left tire only has 37psi this morning, these marks are present and there's some gloss in that area at the edge of the tread. On the right tire, at 39psi, those marks are scrubbed off, and there is evidence of uniform wear in that area at the edge of the tread. There is no evidence of any scrubbing on the sidewall itself below the tread edge line.

Given all the available evidence, I'm wondering:
1. Is it even possible to do this to a wheel just by driving if you don't hit anything?
2. Is it possible that wheel camber could contribute to this if it's set wrong?
3. Is it possible that a damaged or loose suspension linkage could cause the whole wheel to rotate enough to cause this?

I am just as puzzled as everyone else who has posted on this seems to be.


Notice the mold marks on the left tire. These are gone on the right tire.

 

How could you scuff it up like that and yet the sidewall looks fine? Puzzling...

 

Man those are HUGE and deep chips.

I'd call one of those quickie wheel repair places and get it fixed. Maybe spend $200 and call it a day. They do a quick spray on it while on the car. Who knows. This is beyond my brain power.

 

You know that's exactly what I've been thinking I'd do, and I have one I've used before that does good work. Even so, I am really baffled by the fact that this happened at all. I mean, I could accept this happening if I checked the tire pressure and found out the tire had only 20 psi in it. Good luck getting the car rental place to believe me, but at least I'd know that's what the likely cause was. But it couldn't be, because I had 39psi.

So then I start wondering whether, "gee, maybe I pushed it too hard into a corner, and I shouldn't have done that (poor little Porsche - can't handle hard cornering)." Ummmm....no (or?). If it turns out that actually is the case then I guess a 991 isn't in my future, ever - I'll stick with the 996, thanks.

Just seems wrong - and I really would like to know. Any of you guys ever autocross your 991? That's the type of cornering forces that we're talking about here - low speed, tight corners with high lateral force. I just can't imagine that this sort of thing happens out there normally - if it did, there'd be a boatload of rashed 20" wheels on 991s.

So that really leaves a couple of possiblities: something mechanically is out of whack, although to my untrained eye I can't see anything like that. And I did drive it on the freeway a few days ago and everything felt normal at speed. Or there was pre-existing damage that someone tried to cover up before they turned it in, and I'm the unlucky next renter who has found it.