[glamcem]

Originally Posted by OminouSS

I almost don't want to open up this can, but.... 26f/27r to start the day. RF at 25 for CCW. But I take air out nearly every session and don't get crazy until they come up to temp. I've been told I under inflate so I've gone the other way on advice and it didn't pan out. Hoosiers I start the day even lower for a target @ 33. This is an area that I am not comfortable giving direction one way or the other as I am learning how each tire reacts to temps and I've had zero training (and the only guidance is what I can find through the great racing book, google). This is a learning phase for me with my new buddy Mr. Pyrometer. I should be asking you; what temps you start the day and what is your end-session target?

Hmm that sounds a bit low for the Hoosiers. Due to their low load rating and sidewall design, Hoosier recommends above 35psi cold for our cars. My friend who had a previos Gen 1LE had a lot of issues when he tried running the Cup 2s with 26PSI cold.

Personal sweet spot is 28 psi cold all around and generally target 34-35 psi hot. Those numbers seemed to be working on all the tires I've owned so far and I slightly adjust the pressures as/if needed. If I notice some understeer I release a 1 lbs of air between sessions so it may be 27/28 or maybe 27 psi all around (depends on the weather also).

I made a mistake and started with 26 psi with Trofeo Rs one time and had to deal with adjusting pressures all day as it's easier to overheat the tires when there is less air in it but in the meantime it felt awkward when I tried with 29-30 psi on NT01s ..etc

My friend who had issues with the Cup 2s had a conversation with Hoosier so it may probably apply to your car as well since the weights are pretty close

You may find the email conversation on the second page. I would personally more concerned about the amount of front camber than the pressures. The lack of camber is killer
http://www.camaro5.com/forums/showthread.php?t=380614

[Norm Peterson]

Originally Posted by glamcem

... I am surprised you managed to keep them below 36 psi at 107 degree until the end of the session. I could easily see 36-37 psi on a much cooler day on a lighter and less powerful car with the OEM tires

Doesn't that mean that the ambient temperature (tire temperature) that cold pressures were taken at was at least somewhere near 107° as well? That the pressure rise would still mainly be a function of how hard the driving was?


Norm

[glamcem]

Originally Posted by Norm Peterson

Doesn't that mean that the ambient temperature (tire temperature) that cold pressures were taken at was at least somewhere near 107° as well? That the pressure rise would still mainly be a function of how hard the driving was?


Norm

I am not sure, it would be an assumption (could be cooler in the morning or a spare set in the trailer). However, I can definitely tell the tire temps and as a result the pressures rise much quicker on a hot day than the cold day. I could tell the difference between two sessions on one afternoon once the ambient temps dropped about 4-5 degrees. I bet there are other factors too but here in PNW, once the sun gets blocked by some clouds temps drop drastically

[OminouSS]

Here in the great valley of the golden state, California...once the sun gets blocked by some clouds, you can go outside.

Traction was superb in the Hoosiers at 33. I did cord the outside in a day, though. I still have to blame it primarily on camber as the temps were consistent within 3-5* from inside to out. Did I mention traction was hero-quality? But now I must consider a trial the other way.

Thanks for that link Glamcem

[JRL1LE]

Originally Posted by OminouSS

Here in the great valley of the golden state, California...once the sun gets blocked by some clouds, you can go outside.

Traction was superb in the Hoosiers at 33. I did cord the outside in a day, though. I still have to blame it primarily on camber as the temps were consistent within 3-5* from inside to out. Did I mention traction was hero-quality? But now I must consider a trial the other way.

Thanks for that link Glamcem

Rob,

I ran Hoosier A6/7's for 4 years, they have better grip at the lower pressures you are at, but they do wear faster. On my C5Z06 I would start at 24, end up 28-30 hot but these cars are heavier, I think you good right there. The grip on the Hoosier's is addicting!

[glamcem]

Originally Posted by OminouSS

Here in the great valley of the golden state, California...once the sun gets blocked by some clouds, you can go outside.

Traction was superb in the Hoosiers at 33. I did cord the outside in a day, though. I still have to blame it primarily on camber as the temps were consistent within 3-5* from inside to out. Did I mention traction was hero-quality? But now I must consider a trial the other way.

Thanks for that link Glamcem

Sure

[OminouSS]

Originally Posted by JRL1LE

Rob,

I ran Hoosier A6/7's for 4 years, they have better grip at the lower pressures you are at, but they do wear faster. On my C5Z06 I would start at 24, end up 28-30 hot but these cars are heavier, I think you good right there. The grip on the Hoosier's is addicting!

Thanks John. Let me know if you would suggest something different than what I had going that day. Addicting as it was, I was willing to give it away for the cups if I could get the damned wheel off. I could see having the R7's on standby for a warm-up and competition, then back to earth. BTW...Patrick gave me a base point for the car finally, yesterday. 24. I told him it was too low. That would put me with you guys on cup2's or NT01's. Although I think on stockers, and you guys on A/R 7's, I lose.

[Norm Peterson]

Some tire temperature stuff that hit my mailbox recently.

http://trackdayzone.com/articles-gen...eid=34cf2dcc6f


Norm

[JRL1LE]

Originally Posted by OminouSS

Thanks John. Let me know if you would suggest something different than what I had going that day. Addicting as it was, I was willing to give it away for the cups if I could get the damned wheel off. I could see having the R7's on standby for a warm-up and competition, then back to earth. BTW...Patrick gave me a base point for the car finally, yesterday. 24. I told him it was too low. That would put me with you guys on cup2's or NT01's. Although I think on stockers, and you guys on A/R 7's, I lose.

Actually, the 24 pts might be high. 25 pts puts you in the next higher class. You have to also take points for larger tires over 275's (1 pt per 10 mm over 275= 3 pts for 305's), so 24 + 3 tire points gives you 27 pts and moves you up one class.

[OminouSS]

Originally Posted by JRL1LE

Actually, the 24 pts might be high. 25 pts puts you in the next higher class. You have to also take points for larger tires over 275's (1 pt per 10 mm over 275= 3 pts for 305's), so 24 + 3 tire points gives you 27 pts and moves you up one class.

You think? Grand sport is 25. I figured it should be in the same class as Z06 to start, yet its not as capable as that car. It's strange because the A7's in a 315 would clearly put ZL1 in that next class but cup2's/NT01's in a 305 is running with the 20pt base points cars (Z28/SS1LE). I think the beauty is the 1LE at 20 base gives you the luxury of running 315 hoosiers right at the threshold of 24. Not that you need it! But it's there should you want. I don't think I would even attempt to stay under 25, therefore I may as well do what I can to compete in the next step up with a full 5 points to play with. This is my first experience at meeting spec and I'll tell you, it's kind of fun! I don't want to run into you with A7's though

Originally Posted by Norm Peterson

Some tire temperature stuff that hit my mailbox recently.


Norm

Thanks Norm. I think my favorite part:

A: Humans are capable of really dumb and extremely brilliant acts. A car like that demands the utmost in respect. Maybe something strange happened but, in the end, the driver is responsible for what the car does.

Aint that the truth that keeps me up at night!

[OminouSS]

John....nevermind. I see your point on 275. So you have to go one way or the other. Either wider or stickier but not both. Interesting.

[JRL1LE]

Originally Posted by OminouSS

I think the beauty is the 1LE at 20 base gives you the luxury of running 315 hoosiers right at the threshold of 24. Not that you need it!

You got it, the tire size points make a big difference.

[PolynesianPowerhouse]

This is just a testament I guess.... from experience this weekend. Drove 10 hours down to NC, and then about 8 hours back today. Recently, I added the front GM splitter. only thing really externally that's been different over the past month or so.

I do have to say, even behind big rigs, when you're in their "wash" the car was more stable.

also never took it out of touring mode for the trip, so the acceleration was gradual and slower response than normal stock. but even when getting up to left lane passing speeds (yes, I was taught and trained in Germany where I grew up to pass and GET OUT THE WAY of others) and making a pass... the car was stable and planted. the last significant trip I took, behind trucks the car def felt the air comin off the trucks.

not really scientific with data, but as for experience, made a huge difference.