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I replaced my rear strut mount last week and was shocked to find the inside of my rear tires split in some places and worn to the cord in others. I glance at them every few weeks and based on the wear indicators I figured I had another 2-5k miles on them. You really have to get on all fours to inspect these tires...
That being said, I cant complain because I still got 20k miles out of these PS4Ss and the handling is great.
My question is if you guys think the inside tread is showing excessive negative camber, or is this normal for these cars?
I got the car aligned by a good race shop after I installed lowering springs last year. They told me they gave it a "conservative" alignment for typical driving conditions.
There’s something off with that alignment. Inside edge wear is normal on the rear of outer cars, but it’s usually evenly graduated across an inch or two of the inside edge. Your tire has a groove at the edge of the tread (or where the tread used to be) and you still have visible sipes directly adjacent to the groove that are not worn.
I dont know what the fix is, but it’s not normal.
Edit: Wayne May be right. Too much toe-in could be grinding that edge excessively.
Too much toe is usually the answer, but that wear seems to be on shoulder of the tire, not the main tread area and not tapered from the center out. The wear does not seem normal and looks to be from rubbing something. I would expect the tread next to the wear to be much thinner and would check for anything loose or rubbing, especially if lowered.
I replaced my rear strut mount last week and was shocked to find the inside of my rear tires split in some places and worn to the cord in others. I glance at them every few weeks and based on the wear indicators I figured I had another 2-5k miles on them. You really have to get on all fours to inspect these tires...
That being said, I cant complain because I still got 20k miles out of these PS4Ss and the handling is great.
My question is if you guys think the inside tread is showing excessive negative camber, or is this normal for these cars?
I got the car aligned by a good race shop after I installed lowering springs last year. They told me they gave it a "conservative" alignment for typical driving conditions.
Never saw wear like that. I've seen similar wear on my three 997's but it's been spread more evenly towards the inner most 2" to 3" like in the picture attached below. That said, you got about double the miles out of that set than I got out of any of mine. I've probably averaged around 11,000 miles on all the rear sets I've had to replace. 20,000 miles on the 997 rears is not often heard of, at least not on lowered cars.
Too much toe is usually the answer, but that wear seems to be on shoulder of the tire, not the main tread area and not tapered from the center out. The wear does not seem normal and looks to be from rubbing something. I would expect the tread next to the wear to be much thinner and would check for anything loose or rubbing, especially if lowered.
Sandwedge's picture shows the sort of wear you should expect from alignment issues. Interesting to me is the fact that the wear is not even around the tire - as your car is lowered I'd be looking for rubbing on something when the suspension is compressed over bumps. It looks more like gouging than rubbing.
The alignment shop went too far and have created a toe-out condition (sometimes called heel). Toe in wears the outer edge of the tire. Toe out wears the inner edge. This wear looks like the product of a lowered car that has too much negative camber and too much toe out. Did you have the car aligned after the lowering springs were installed or before?
In the rear you want very close to zero toe or some slight toe in and not much camber - I actually set my wife's outside the alignment spec from Porsche. You want enough front toe in where during suspension travel and steering geometry you never create a transition from toe in to toe out, which can create a very unstable car. In the rear, toe shouldn't change. You got 20,000 miles out of those tires, but they've probably been unsafe on that inner edge for 3,000 miles or so.
Here's a good, conservative alignment spec for street use. This is what we use in my wife's car and she sees 17-18k miles out of a set of rears before any cord shows.
See how that compares to your current setup once you put it on the rack. Make sure when you get the new tires o that you don't immediately take it into high speed corners to see how the new alignment settings handle - you need to wear through the mold release on the tires, which is slippery for the first few hundred miles.
Can you post a pic of your toe eccentric adjustment?
On a lowered car it should be maxed out, and even then the factory adjusters are only able to give you toe at the high end max permissible. Adjustable rear toe links are the answer for long tire life on lowered cars.
Just saw Petza post, actually it is impossible to have toe out on a lowered car with factory eccentrics, unless something is really screwed up.
as your car is lowered I'd be looking for rubbing on something when the suspension is compressed over bumps. It looks more like gouging than rubbing
Well now you've got my attention. I will be mortified if I've been driving around with my rear tires rubbing on my control arms :-) Thats the only thing I can imagine they could touch. Wayne had his head in the wheel well while I was under the car last week and neither of us saw anything obvious.
Steel belt separation has caused similar wear to this on some of my rear tires on my suv. But those tires have had 80-100,00 kms on them. The wear occurs on only one section of the tire on the inner edge. A wobble in the vehicle can usually be felt at low speeds, at high speeds it is not detectable. The wear usually extends in about 1/8 - 1/4 of the tread, like Sandwegde's picture , where as yours does look like rubbing but it could be a variation.
The alignment shop went too far and have created a toe-out condition (sometimes called heel). Toe in wears the outer edge of the tire. Toe out wears the inner edge. This wear looks like the product of a lowered car that has too much negative camber and too much toe out. Did you have the car aligned after the lowering springs were installed or before?
In the rear you want very close to zero toe or some slight toe in and not much camber - I actually set my wife's outside the alignment spec from Porsche. You want enough front toe in where during suspension travel and steering geometry you never create a transition from toe in to toe out, which can create a very unstable car. In the rear, toe shouldn't change. You got 20,000 miles out of those tires, but they've probably been unsafe on that inner edge for 3,000 miles or so.
Here's a good, conservative alignment spec for street use. This is what we use in my wife's car and she sees 17-18k miles out of a set of rears before any cord shows.
See how that compares to your current setup once you put it on the rack. Make sure when you get the new tires o that you don't immediately take it into high speed corners to see how the new alignment settings handle - you need to wear through the mold release on the tires, which is slippery for the first few hundred miles.
Pete you never cease to amaze. I would need to trade-off the basic motor functions of my brain to try to keep all this car knowledge in my head :-)
I did the alignment after I installed the new springs. I waited a few days to let them settle but I'm thinking...maybe they didn't settle enough. I did put 15mm spacers on after the alignment and maybe that threw it off (they said it wouldn't).
Let me find my original alignment spec from S-Car-Go.
Pete you never cease to amaze. I would need to trade-off the basic motor functions of my brain to try to keep all this car knowledge in my head :-)
I did the alignment after I installed the new springs. I waited a few days to let them settle but I'm thinking...maybe they didn't settle enough. I did put 15mm spacers on after the alignment and maybe that threw it off (they said it wouldn't).
Let me find my original alignment spec from S-Car-Go.
You crack me up.
There's really nothing for the inside edge of that tire to rub on back there other than a brake cooling scoop or the coil spring or inner fender, but with 15mm spacers you can be close to the inner well or the coil and the plastic brake scoop, if you have them, would wear out before the tire rubber.
I think it's the spacers that exaggerated it. Moving the wheel out 15mm has lengthened the moment arm of the suspension so it now has more torque on that control arm and I bet has increased your negative camber. You should be able to see this when they start the alignment and log the before values, comparing them to the printout you have from the previous alignment.
Here are pictures with a wheel installed and you can see there's nothing really in that wear area.
11-16-2018, 12:53 AM
997 tire wear: normal or too much camber?
