GT radial SX2 track owners question about PSI

[jflogerzi]

What PSI do you run hot on track? Trying to figure out what is the best/optimal PSI...

I run 245s on a 17x8 wheel

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[CSG Mike]

Depends on your setup and preference. There is no universal one best, just how your tune is customized to your setup.

Use a pyrometer. You're welcome to borrow mine as long as you don't damage it.

[jflogerzi]

Yup I get that.

Setup mostly in sig. Suspension is stock 17 non pp dampers, rce yellows, and peddlers top hats. I have a whiteline 20mm sway bar up front on stiff and a 2017+ oem rear sway out back. Alignment is -2.3 up front and -2.2 in the back

I normally shoot for 30-32psi hot. I feel like the higher it goes the less grip the car has...

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[Pat]

I like 34 hot with 225 45 17 SX2s on an 8" wheel. 3.6* front camber, 2.5* in the rear.

[CSG Mike]

most of the socal records are held by 37-40psi hot

[jflogerzi]

Really wow... So excuses my ignorance what's the benefit of having a higher PSI vs lower PSI

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[Pat]

Originally Posted by CSG Mike

most of the socal records are held by 37-40psi hot

Hmm.. very interesting. I wonder what the rest of their setup is like.

[Pat]

Originally Posted by CSG Mike

most of the socal records are held by 37-40psi hot

So maybe they go out and turn a fast lap with cold tires at 34 and by the time they are done they are up to 40 hot? Or do you really think the fastest laps are turned with tires between 37 and 40?

[CSG Mike]

Originally Posted by Pat

Hmm.. very interesting. I wonder what the rest of their setup is like.

Stock class car in many instances, so.... quite literally a stock car, with a 17 rear sway, and camber modification, brake pads, and oil cooler.

In the case of William's car, -4ish front camber, -2.7ish rear camber, 0 toe front/rear.

His fastest laps are typically laps 6-10.

[CSG Mike]

Originally Posted by jflogerzi

Really wow... So excuses my ignorance what's the benefit of having a higher PSI vs lower PSI

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There isn't. That's where it happened to end up when tuned by pyro.

[SCFD]

Originally Posted by CSG Mike

Stock class car in many instances, so.... quite literally a stock car, with a 17 rear sway, and camber modification, brake pads, and oil cooler.

In the case of William's car, -4ish front camber, -2.7ish rear camber, 0 toe front/rear.

His fastest laps are typically laps 6-10.

Why a rear sway bar instead of front?

[jflogerzi]

Originally Posted by CSG Mike

There isn't. That's where it happened to end up when tuned by pyro.

I need to read up on these pyro tire devices.

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[CSG Mike]

Originally Posted by SCFD

Why a rear sway bar instead of front?

Rotation.

We don't really slalom on tracks the way you do in AutoX, so there's not a reason for giant front sway.

[Pat]

Abe and I were talking about these hot tire pressures that set lap records in SoCal. We still struggle to understand how this is possible given our data. I could understand one or two PSI difference but six is really difficult to comprehend. Especially when I can feel 35 is too hot relative to 34. I have a lot to learn.