Tire pressures for Firehawk Indy 500 tires for track/autox

[bullitt2]

Hi all,

Sorry if this is a duplicate but I couldn't find any info specific to these tires. I have contacted Firestone with no response. I'm wondering if anyone has any insight into roughly what tire pressures to run cold/hot on these tires? I have a base 2015 GT and run it in intermediate track day lapping groups and autocross. Spent last season as a beginner with the all season Pirellis that came with the car when I bought it used. As such, I didn't have to worry too much about tire pressures. Now that I am posting quicker lap times, they are becoming an issue.

Can anyone advise roughly what tire pressures they would recommend running on these tires? Not used to softer summer tires. I am running square set-up with OEM specs of 235/50/18.
My last track day was on a 9 turn 1.4mi track and I was running about 31 cold and then 34-36ish hot. I'm going to start using a notebook to track the pressures.

Any info on this would be great. Thanks in advance!

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[BmacIL]

Hi all,

Sorry if this is a duplicate but I couldn't find any info specific to these tires. I have contacted Firestone with no response. I'm wondering if anyone has any insight into roughly what tire pressures to run cold/hot on these tires? I have a base 2015 GT and run it in intermediate track day lapping groups and autocross. Spent last season as a beginner with the all season Pirellis that came with the car when I bought it used. As such, I didn't have to worry too much about tire pressures. Now that I am posting quicker lap times, they are becoming an issue.

Can anyone advise roughly what tire pressures they would recommend running on these tires? Not used to softer summer tires. My last track day was on a 9 turn 1.4mi track and I was running about 31 cold and then 34-36ish hot. I'm going to start using a notebook to track the pressures.

Any info on this would be great. Thanks in advance!

What sizes?

Typically I'd recommend around 36-37 hot up front to help with the sidewall, and 31-32 hot rear.

 

[bullitt2]

What sizes?

Typically I'd recommend around 36-37 hot up front to help with the sidewall, and 31-32 hot rear.

Sorry I edited the post because I realized I forgot the size. Square set up with 235/50/18. You think I was running too low then?

 

[strengthrehab]

I found my best results with about 36-38 hot all around. If they were higher, the tires lost grip and lower they were too sketchy due to soft sidewall, especially in transitions.

My setup is 285/35/19 on 19x10 square setup. I know above 38, The car skates around pretty good on 285's . I couldn't imagine 235's . Yikes.

 

[sonicc]

Kind of a noob question - but do you guys check your hot pressure immediately after the session or let it cool off for a few minutes? I've been just setting my pressure cold at around 36-38 psi, but I think it's time to start playing with this. Also gonna try making a few marks with chalk and keep an eye on that.

 

[strengthrehab]

Thise cold pressures are way too high in my opinion. If I started there, I'd be 43 plus hot and it would be like skating.

Then again I'm in Texas and drive like an idiot.

As far as when to check? Unless you have a 2nd or 3rd person check them in hot pit, you can only check when you park...that's when I do it.

 

[NightmareMoon]

Check them between runs as close to when you finish as you can reasonably check them. Most tires I’ve seen need to be kept at or below 37psi HOT or they give up grip. (So cold pressures 2-5psi below that)

The front tires will scrub down past the shoulder tread if pressures are too low, so thats what you’re checking. Look for the tread wear indicators moulded into the shoulders and spaced out around the tire. They’re often little triangles less than a quarter inch in size, but different tire brands use different shapes. You want to scrub down to those markers and not past (for a starting point)

You will probably find you can run a bit lower pressure on the rear axle vs the front because of the geometry and the way the rear tires get used.

 

[NightmareMoon]

Here’s a pic of the tread wear indicators on the indy 500.

 

[EFI]

Not to go off track here, but all seasons on a track?? Or 235 tires for a 3700lb car?

Why not get some better & wider rubber on there? You have all the room in the world to run 295s and you don't have to be a pro to use that grip.

 

[BmacIL]

Not to go off track here, but all seasons on a track?? Or 235 tires for a 3700lb car?

Why not get some better & wider rubber on there? You have all the room in the world to run 295s and you don't have to be a pro to use that grip.

This being the biggest issue.

 

[NightmareMoon]

Yeah, if you don’t already have 235 Indy 500, getting some take-off mustang wheels in a wider wheel size would be worth it.

If you’ve already got them, just run what you have and look at upgrading later.

 

[PoppinJ]

I never even knew about the wear indicators on the tires for roll over scrub. Does the PS4 have them? I was looking and didn't see any.

 

[shogun32]

but all seasons on a track?? Or 235 tires for a 3700lb car?

Why not? The point is to learn how to maximally utilize what you have. Not overcompensate with bigger/stickier rubber that you're not good enough to stress.

 

[BmacIL]

Why not? The point is to learn how to maximally utilize what you have. Not overcompensate with bigger/stickier rubber that you're not good enough to stress.

Because at that size, the tires have a difficult time properly handling high performance driving with a car this heavy and powerful. Believe me, I unfortunately know. A tire 255 or wider, even A/S, responds and handles much more predictably on this platform. The goal isn't speed, but learning to push what you have and go quicker.

 

[MasterCylinder]

I keep my as close to 40 as possible. I prefer to try and keep the drag from too much grip down.

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