Is this tire feathering?

fairladyATX

Michelin Pilot Sport 4S tires, these are the front wheels. I'm unsure of the mileage on them, but they have 2 track days where I'm pushing them fairly hard. e.g. Novice group -- but tire traction is a limiting factor.

I just started my usual prep for COTA next week and noticed the inside of my front wheels look like this.

Camber is maxed in the front, which explains the wear pattern, but what is going on with the little pieces of rubber on the inside?

Link to image since the below one is massive and I'm unsure on how to resize it: https://imgur.com/a/ReK9eDJ

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Averying

Id guess this is just a weird result of overheating a primarily street-focused tire. I’ve heard they overheat pretty quickly after a few hot laps so they probably deteriorate quickly when you push them hard. Did you watch your pressures as the day went?? And what do you mean by ‘camber is maxed’? What degree of camber do u have

I’m putting some PS4S on in the spring and plan on an occasional track day so I’ll try to go easy on them


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fairladyATX

I do remember saying the instructor thought I was overheating them, we kept on dropping pressure out throughout the day. At the end of some sessions, they were 40-42psi, even when starting cold around 30-32. They would get slick, car would just slide (which is super fun -- but not ideal obviously)...

Alignment specs:
FRONT: Left / Right
Camber: -1.6 / -2.1
Caster: 6.0 / 5.8
Toe: 0.10 / 0.08
Total toe: 0.17
Steer Ahead 0.01

REAR: Left / Right
Camber: -3.2 / -2.9
Toe: 0.18 / 0.22
Total Toe: 0.40
Thrust: -0.02

Another guy was running the 4S's on his Audio RS4, had a similar issue but on the outside of his tires. 4S's def are not track tires -- guess I'll have to see if I can get a new set of tires before next weekend.

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Rusty

Yeah, it's feathering. If this is on the rear inside. You got too much camber. You don't need over -2 camber in the rear. The Z has a wicked camber curve in the rear.

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Averying

This. Is on the front with minimal camber so it’s a little surprising. See OPs post above

Edit: OP did u mix up front and rear camber? They seem opposite of normal?

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fairladyATX

No, that's correct. If I recall correctly, the front camber isn't adjustable, and I think Firestone maxed out the rear for some reason, need to get that back in spec.

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Tractionless

Says inner on the fronts.

OP,

Suspension setup is not mentioned, incorrect/insufficient rebound can also cause such issues. Wear to and/or type of dampers is important.

If tracking you're car I'd also stay away from Firestone and find a road race shop who will take more time and has the knowledge/patience to do it properly. There has to be plenty near COTY to chose from.

I have mine done by such a shop for my spirited street car. It takes an hour and a half for the entire procedure with complete OE front and rear suspension with aftermarket rear camber and toe adjusters in the rear only. Even longer if I had A-arms, coil-overs and the rest of the goodies of many members here. Expect multiple hours if/when you jump into corner weighting.

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fairladyATX

Mostly stock suspension: Eibach Pro springs, stock shocks, Hotchkiss front sway on front. Come to think of it, I don't think I had any feathering on my 1st track weekend. The alignment and the sway bar went on before the 2nd track day.

Think I'll get the car re-aligned closer to spec and just keep a close eye on these 4s's at the track. Time for a dedicated wheel/tire setup I suppose.

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Tractionless

Mileage on the shocks?

OE front max camber is -1.25 so you're over by quite a bit. That paired with the new stiffer front sway bar may be causing the push which may be the feathering culprit (traction loss resulting in slide). A stiffer front sway bar decreases front grip/traction which will be compounded by less tire on the road due to high negative camber. Basically overloading the inside of the fronts as a result.

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fairladyATX

I believe they are the original OEM shocks, so 77k miles on them.

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Spooler

You need to vist SPL and buy the stuff to get your car alignment setup correctly.

Tractionless

You're asking a lot of 8 year old 77k shocks to do track duty with springs that may/may not be a good match for them. I don't have enough knowledge in the spring/shock mating options as I never considered lowering mine, but have seen multiple threads over the years of springs OE shocks don't play with well.

Do a search of threads with your spring type and see what you can find.

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Averying

I’m also thinking it’s something to do with the older OEM shocks. Seeing as he’s got less than 2° of camber in the front, it seems weird that the inside of the front tires are so beat up. I mean a lot of track guys have the same front bar, with a lot more front camber, and I don’t think this is a typical problem.

Now I’m surprised that you’re not having a similar problem in the rear with over 3° of camber…


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fairladyATX

Yeah -- agreed, but after I get full coilovers. Been spending more money on track time than parts recently, but looks like I'll need to swap that soon.

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