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Old 11-25-2019, 12:51 PM
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Default Edge tread wear

I don't know why I didn't think of this forum earlier. Driving a Cayman I went to the Cayman Register first, but this is really a more general track issue and I've found members of this group to be very well informed.

I run PS4S on a Cayman and this year managed to cord the edges (after 13 track days) while I still had a lot of tread in the middle. Attached are photos of the left side pair and the right side pair. I try to run at about 35-37# hot which works well.

I'm not sure why. Pushing too hard is one possibility. Someone suggested I needed more sidewall stiffness but I always though the PS4S were fairly stiff; maybe I'm wrong. If so, I could use suggestions. A third possibility is this is just normal; tires and pads are consumables . Anyhow, I am looking for comments, ideas, suggestions.
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Old 11-25-2019, 01:17 PM
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I'm sure others know much more about this than me, but the same happens with me, and I assume the big culprit is negative camber. It is my assumption that lots of hard braking on wheels with significant negative camber will be hard on the inner edges of the tires. I guess driving in general with negative camber puts wear on the inner edges of the tires.

I have been in the habit of having my NT01's remounted after a few track events so that the inner edges become the outer edges. This has given me some extra wear.

This year I did not do many track events, but before hitting the track I installed camber plates up front to get a lot more negative camber. Before I got around to remounting the tires I had corded the inner edges of my front tires.
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Old 11-25-2019, 01:20 PM
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That is pretty normal. If you ran enough camber to avoid this you would likely hate driving the car on the street. One way to increase tire life is to flip the tires on the wheels after a certain amount of track days (this only works if the tires are not asymmetrical).
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Old 11-25-2019, 01:30 PM
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Ah, I was thinking inside edges, as this is what I am dealing with now. If it is the outside edges, then as David suggested you could consider more camber.
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Old 11-25-2019, 01:46 PM
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Good point -- he could be talking about inside edges. That could be a sign of too much negative camber as you suggested. Definitely much rarer to have that happen on the track, but seen it a bit on cars that have a track-oriented alignment but get driven on the street a lot with the same tires.
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Old 11-25-2019, 02:53 PM
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I wore out and chunked the outer edges on my PS4's running autox. Not sure of the Cayman R's are different, but in stock form there is very little negative camber to be had on these cars. For street driven tires (and certainly for those of us abiding by class rules), I doubt much can be done.
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Old 11-25-2019, 04:40 PM
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Quote:
Originally Posted by rbpeirce View Post
I don't know why I didn't think of this forum earlier. Driving a Cayman I went to the Cayman Register first, but this is really a more general track issue and I've found members of this group to be very well informed.

I run PS4S on a Cayman and this year managed to cord the edges (after 13 track days) while I still had a lot of tread in the middle. Attached are photos of the left side pair and the right side pair. I try to run at about 35-37# hot which works well.

I'm not sure why. Pushing too hard is one possibility. Someone suggested I needed more sidewall stiffness but I always though the PS4S were fairly stiff; maybe I'm wrong. If so, I could use suggestions. A third possibility is this is just normal; tires and pads are consumables . Anyhow, I am looking for comments, ideas, suggestions.
It's hard to tell for sure from the tiny pics you posted, but it looks like you trashed the outside edges of your tires. On that assumption:

As pointed out earlier, this is primarily due to a lack of sufficient negative camber. However, putting in enough camber to prevent this will make the car far less pleasant to drive on the street and could be rather $$$ by the time you buy & install all the parts needed to get that camber.

A way to mitigate the wear you experienced is to upgrade your sway bars. IMO, upgrading sway bars is the most cost-effective suspension improvement you can make to a 987 (either gen). I did it to both of my past 987s, one of which was an R, and it greatly reduces the outside-edge wear without affecting ride quality too much. I've recommended this to other people as well, and they also saw improvement in outside-edge life.
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Old 11-25-2019, 06:41 PM
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Keep in mind also that 13 track days is a lot longer than many see from set of tires. Track settings and street settings are not compatible for most folks. You can set things sort of in the middle and compromise both a bit. As said a good track setup is a chore and eats tires on the street.
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Old 11-25-2019, 06:44 PM
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Quote:
Originally Posted by BillC View Post
A way to mitigate the wear you experienced is to upgrade your sway bars. IMO, upgrading sway bars is the most cost-effective suspension improvement you can make to a 987 (either gen). I did it to both of my past 987s, one of which was an R, and it greatly reduces the outside-edge wear without affecting ride quality too much. I've recommended this to other people as well, and they also saw improvement in outside-edge life.
Okay. This is a totally new idea to me. I'm assuming you are suggesting stiffer settings, but how does that work? I suspect it would tend to unload the inner wheels a bit but how does that help the outside?

Sorry about the small pics. Your web site uploads them and does what it wants. I tried clicking on them to see if they could be made bigger but no luck.
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Old 11-25-2019, 08:32 PM
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Use a photo editing program to change the max pixel dimension to 2000 (or less) and they will become bigger.

Stiffer means less body roll which means in most cars a bit less camber disturbance. Stiffer also opens up another level of suspension tuning, both good or bad depending, as ARB rates work in conjunction with other aspects.

as said a short term adjustment is to run symmetrical tread tires and flip them on the rim after a few days.

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