photo of my tire folding over in a corner

[alex.s]

i wonder if its bad for the tire
lol anyone know what hot pressure i should run these at?

[Scrappydoo]

It's not "folding", it's flexing.

It's perfectly normal and doing what a tyre should do.

A tyre with a stiffer sidewall will do it less but ultimately may not give more grip.

[alex.s]

Originally Posted by Scrappydoo

It's not "folding", it's flexing.

It's perfectly normal and doing what a tyre should do.

A tyre with a stiffer sidewall will do it less but ultimately may not give more grip.

It seems like it gets to a certain point and gets noticably worse though. Not in this photo. Don't have a photo of it. Can it fold all the way over to where the bead is hitting?

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[dattran86]

its normal while turning at hard.

KLIN0131_PP-2 by Apex 86, on Flickr

you can add more tire pressure if you want to avoid running down the side wall.

more psi = less tire contact with the surface
less psi = more tire on the surface

lesser psi tend to run the sidewall down if you're corning hard. just play around with the psi and see what work for you

[Scrappydoo]

Originally Posted by alex.s

It seems like it gets to a certain point and gets noticably worse though. Not in this photo. Don't have a photo of it. Can it fold all the way over to where the bead is hitting?

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No.

Is this your first car?


Ask yer dads dad about crossplies

[alex.s]

Originally Posted by Scrappydoo

No.

Is this your first car?

No this isn't my first car. But it's my first car on track. Only motorcycles before this which have completely different tire setups...

I think my tire pressure was too low. On certain turns it definitely was worse... It didn't feel like hitting bump stops. It felt like after a certain point the car would hunch a little bit more and it would be very rough sounding (not just normal tire scream)/feeling through the steering. the feeling i know of bottoming out a shock is more of a force away from the lean and then often a jerk back into it as the tire slides from the suspension pushing it.... but maybe that's different on cars vs bikes?

The tire was pretty warm... I wonder if I had too low of pressure and it was overheating the tire and turning it to jello

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[Silver Supra]

Too low tire pressure would do that. @dattran86 had it right. You need to check tire temps and wear during track days to find a good pressure for your setup. Adjust as required for ambient conditions.

[Ultramaroon]

Regardless of how it's sold, the car is set up to understeer. Yes, it's normal for daily use by the lay-driver. For anyone wishing to explore more neutral bias, the first step is adding negative camber to the front wheels.

Although any added negative camber will have a noticeable effect, -3 degrees is a popular target.

[OND]

In my experience, the front tires first start singing, then start screaming, then start vibrating and shaking the steering wheel.

The third case is probably what you are feeling. It happens when you way overcook the corners and add too much steering input. I guess it would happen less with higher pressures and stiffer sidewalls, but it is a pretty good indication of overdriving the front end, so I'd fix that first.

I started using 32psi cold based on the suggestions on the forum and it works really well for me. Gives me around 38-39psi hot.

[alex.s]

Originally Posted by OND

but it is a pretty good indication of overdriving the front end, so I'd fix that first.

could you expand on this please? the places it happened were the second swing of a very tight chicane... which i often wind up with like 5-10* slip angle on the front through if i give it more than just a little gas, and in two corners which are both high speed flat out... i would think more gas would help the front tires be less loaded... but it seems like if i do things to try to unload the front it just understeers

i thought it could be weight transfering too fast, but that's really not the case in the high speed corners... might be the case in the chicane. but i'm not sure how to setup the last corner correctly without changing the car direction quickly... i try to be as smooth as i can about it and easy into and out of things but maybe i'm just being too rough.

[alex.s]

Here's the tire now

[OND]

Originally Posted by alex.s

could you expand on this please? the places it happened were the second swing of a very tight chicane... which i often wind up with like 5-10* slip angle on the front through if i give it more than just a little gas, and in two corners which are both high speed flat out... i would think more gas would help the front tires be less loaded... but it seems like if i do things to try to unload the front it just understeers

i thought it could be weight transfering too fast, but that's really not the case in the high speed corners... might be the case in the chicane. but i'm not sure how to setup the last corner correctly without changing the car direction quickly... i try to be as smooth as i can about it and easy into and out of things but maybe i'm just being too rough.

What I described never happened to me at high speed sweepers, so maybe that's not exactly your case. It usually happened when I braked too late and fed in too much steering while still braking hard. It seems to be correlated with too much slip angle as you mentioned.

My issue was at corner entry and what fixed the issue was braking slightly earlier and not asking the front end to both brake hard and turn in. If your issue is at corner exits, you should remember not to add more steering when car understeers. Instead, back down on throttle. If you keep adding steering when you experience understeer, you will get the vibrating issue. If you look at a grip vs slip angle graph, you will see why it makes no sense to add more steering once you are at the limit of grip.

Hope this helps your situation.

[OND]

Originally Posted by alex.s

Here's the tire now

Are the sidewall marks going all around the tire? It might just be from rubbing a kerb maybe?

Otherwise, the wear on stock tires look like what I had with mine. Stock 0 camber and the hard tire compound is a bad combination.

Add some heat and overdriving and you will get this:

http://www.ft86club.com/forums/showthread.php?t=112935

[venturaII]

How many psi were you running? I assume everything else is stock as well as the wheel/tire combo? Try adding/subtracting 2- 3 psi at a time, at one end at a time, and then adjust accordingly in 50% increments from there based on feel/grip/wear. Looks like you're just driving the car the way it was meant to be driven...lol.