Optimal track Tire pressure stock zcp?

[NYG]

Originally Posted by Powerslide

For me - When I had the stock MPSS 20" tires - first morning session cold psi was 34. Kept checking and bleeding air throughout the day so that the hot psi stayed around 38-39psi - maintained pretty good control and tires did not get greasy.

Now have RE-71R's on - yeah baby!!!!

Were you at the audible limit of grip on the tires in corners? I'm sure there's people who successfully run that pressure. I just have no luck with it.

[Powerslide]

Originally Posted by NYG

Were you at the audible limit of grip on the tires in corners? I'm sure there's people who successfully run that pressure. I just have no luck with it.

I believe I was very close - but maybe not right at - the audible limit - it was a "nice" tire squeal rather than the bad sounding groan when you're basically right at the limit

[David0ff]

I find that the greatest grip happened around 33F 31ishR Hot on any tire I tried, this usually requires starting around 25f&r cold and bleeding some after 1-2 sessions

[OhioRiderAaron]

Originally Posted by NYG

I said 26 psi cold . That gets me to 32 psi easily after one session in 75 degree weather. Even higher on a hot day.

I've done it plenty of times with super sports. Now I just show up to the track at my standard cold pressure of 34 and bleed them throughout the day.

Yeah, I'm not sure how my previous post can get misinterpreted lol.

PS4S chunk so badly at 40 psi. I had the best results at 35 psi with those.

I seldom meet anyone in an f8x that runs their pressures at ~40 psi with typical tires we all use but we've all got unique driving styles I guess.

Sorry you said 26PSI cold in the previous post and just now said 34PSI cold, it's a bit confusing to me. You must be nearly driving on the edge of the rim during those first few laps in the morning. TPMS light must be on too?

Tires chunk due to being over-driven, it doesn't matter if it's at 30PSI or 45PSI.

I seldom meet anyone who is remotely fast in an F8X so maybe that's part of the reason you never run into anyone running ~40PSI. I get it, no one believes me when I say you have to run that much pressure, but it's a fact for this car and those tires. It produced the fastest laps for me and didn't damage the sidewall (again tried all the way down to 34-35PSI hot with both MPSS and RE71Rs). While I'm not a racecar driver, I do have some of the faster laptimes on the Midwest tracks so I like to think I'm not completely clueless (my coworkers would debate this of course lol).

Originally Posted by David0ff

I find that the greatest grip happened around 33F 31ishR Hot on any tire I tried, this usually requires starting around 25f&r cold and bleeding some after 1-2 sessions

On the F8X, or on a different vehicle? Each chassis and tire seem to have different optimum pressures.

[David0ff]

Originally Posted by OhioRiderAaron

Sorry you said 26PSI cold in the previous post and just now said 34PSI cold, it's a bit confusing to me. You must be nearly driving on the edge of the rim during those first few laps in the morning. TPMS light must be on too?

Tires chunk due to being over-driven, it doesn't matter if it's at 30PSI or 45PSI.

I seldom meet anyone who is remotely fast in an F8X so maybe that's part of the reason you never run into anyone running ~40PSI. I get it, no one believes me when I say you have to run that much pressure, but it's a fact for this car and those tires. It produced the fastest laps for me and didn't damage the sidewall (again tried all the way down to 34-35PSI hot with both MPSS and RE71Rs). While I'm not a racecar driver, I do have some of the faster laptimes on the Midwest tracks so I like to think I'm not completely clueless (my coworkers would debate this of course lol).



On the F8X, or on a different vehicle? Each chassis and tire seem to have different optimum pressures.

On my F82 M4

This year alone I racked up around 4000 kms on the track.
I always drive DSC off, so I have a good understanding of grip and tire breakaway.

As I am still perfecting the car setup and my driving, I am still not using "sticky" tires yet but soon will throw on some CUp2s

My experience with tire pressures and grip is based on these 2 tires models:
-MPSS ( 255F/275R)
-Firestone Indy 500 (275F/285R & 285F/325R)

In both cases anything over 35-36 hot will feel like the car hits an ice patch and you get decreased braking... mid corner skids either front or rear and significantly reduced after apex rear grip

In terms of suspension and brakes I have experience with these setups:
- Stock Suspension & Brakes
- H&R Super sports & Stock Pads
- H&R with Hawk HP Plus Fronts only + Motul 600
- H&R with Hawk HP Plus all around + Motul 600
-Ground Control Coilovers + Camber pates with HP Plus all around + Motul 600

No matter what I did to the car.. unless I keep my tires in the 32-33 tops hot range grip suffers for braking, cornering, acceleration.

Hope this helps

[NYG]

Originally Posted by OhioRiderAaron

Sorry you said 26PSI cold in the previous post and just now said 34PSI cold, it's a bit confusing to me. You must be nearly driving on the edge of the rim during those first few laps in the morning. TPMS light must be on too?

Tires chunk due to being over-driven, it doesn't matter if it's at 30PSI or 45PSI.

I seldom meet anyone who is remotely fast in an F8X so maybe that's part of the reason you never run into anyone running ~40PSI. I get it, no one believes me when I say you have to run that much pressure, but it's a fact for this car and those tires. It produced the fastest laps for me and didn't damage the sidewall (again tried all the way down to 34-35PSI hot with both MPSS and RE71Rs). While I'm not a racecar driver, I do have some of the faster laptimes on the Midwest tracks so I like to think I'm not completely clueless (my coworkers would debate this of course lol).



On the F8X, or on a different vehicle? Each chassis and tire seem to have different optimum pressures.

No.

I deflate to 26 cold to get me in the approximate range of hot pressures I like but I typically get too lazy and just run my street cold pressures and then deflate each session.

I let the tires heat up a little bit before I go nuts with them.

Tires chunk from inherent material properties of the compound and heat. Ideal gas law. More Pressure = More Heat. That's not to say that overdriving a tire doesn't contribute to it but it's way too general.

I don't doubt that you're a great driver, I've seen your vids but you also tell me that you've never boiled your stock brake fluid. I just got back from NJMP with boiled Motul 600 so yeah.

[NYG]

Originally Posted by David0ff

On my F82 M4

This year alone I racked up around 4000 kms on the track.
I always drive DSC off, so I have a good understanding of grip and tire breakaway.

As I am still perfecting the car setup and my driving, I am still not using "sticky" tires yet but soon will throw on some CUp2s

My experience with tire pressures and grip is based on these 2 tires models:
-MPSS ( 255F/275R)
-Firestone Indy 500 (275F/285R & 285F/325R)

In both cases anything over 35-36 hot will feel like the car hits an ice patch and you get decreased braking... mid corner skids either front or rear and significantly reduced after apex rear grip

In terms of suspension and brakes I have experience with these setups:
- Stock Suspension & Brakes
- H&R Super sports & Stock Pads
- H&R with Hawk HP Plus Fronts only
- H&R with Hawk HP Plus all around
-Ground Control Coilovers + Camber pates with HP Plus all around

No matter what I did to the car.. unless I keep my tires in the 32-33 tops hot range grip suffers for braking, cornering, acceleration.

Hope this helps

+1

[OhioRiderAaron]

Originally Posted by NYG

No.

I deflate to 26 cold to get me in the approximate range of hot pressures I like but I typically get too lazy and just run my street cold pressures and then deflate each session.

I let the tires heat up a little bit before I go nuts with them.

Tires chunk from inherent material properties of the compound and heat. Ideal gas law. More Pressure = More Heat. That's not to say that overdriving a tire doesn't contribute to it but it's way too general.

I don't doubt that you're a great driver, I've seen your vids but you also tell me that you've never boiled your stock brake fluid. I just got back from NJMP with boiled Motul 600 so yeah.

Yup that's what I suggested as well. That way you never have to deal with an air compressor.

I may very well have boiled my fluid in the past, but I've never lost brakes either so that's why I continue to run OEM fluid (also tried Motul).

The higher end of the pressures definitely feel looser than the low pressures, but I judged them by laptimes only, where +0.5s was noticeable on either side of the nominal. Again not an expert/time-trial/racer here.

No need to beat a dead horse, everyone has a different experience behind the wheel my bad for giving you crap.

[NYG]

Originally Posted by OhioRiderAaron

Yup that's what I suggested as well. That way you never have to deal with an air compressor.

I may very well have boiled my fluid in the past, but I've never lost brakes either so that's why I continue to run OEM fluid (also tried Motul).

The higher end of the pressures definitely feel looser than the low pressures, but I judged them by laptimes only, where +0.5s was noticeable on either side of the nominal. Again not an expert/time-trial/racer here.

No need to beat a dead horse, everyone has a different experience behind the wheel my bad for giving you crap.

What pads are you running? My 11s cook my entire system.

[Tommix]

I need some advice about tire pressures for track day. Style 437M rims, tires are Federal 595RS-RR, front 265/35-19 and rear 275/35-19.
Tire pressure for this setup?

[SYT_Shadow]

Originally Posted by Tommix

I need some advice about tire pressures for track day. Style 437M rims, tires are Federal 595RS-RR, front 265/35-19 and rear 275/35-19.
Tire pressure for this setup?

I default to around 35-38 psi hot for all tires, it's a good rule of thumb

[ABenLauda]

On street - 32-33 psi
On track - 27-29 psi cold which becomes 35-38 psi after a 30 min session.

[Suds]

I have found hot pressures of 32-34 is best on NT01’s.
When the tires get to 35-36 the grip is falling off.
The question always is, what is the starting temperature at the beginning of a session?
Last weekend I finally was down to the correct starting pressure at the beginning of the session, 26.5 psi and I was able to run fast laps for 30 minutes.
It took a number of sessions to get there.

[Tommix]

Thanks guys for the good info! Has anyone used pure nitrogen instead of air in tires? Is there any advantage? I know that many race cars use nitrogen instead of air in their tires because nitrogen has a much more consistent rate of expansion and contraction compared to the usual air.

[MyNameIsNotSure]

Originally Posted by SYT_Shadow

I default to around 35-38 psi hot for all tires, it's a good rule of thumb

Originally Posted by ABenChod

On street - 32-33 psi
On track - 27-29 psi cold which becomes 35-38 psi after a 30 min session.

Originally Posted by Suds

I have found hot pressures of 32-34 is best on NT01’s.
When the tires get to 35-36 the grip is falling off.
The question always is, what is the starting temperature at the beginning of a session?
Last weekend I finally was down to the correct starting pressure at the beginning of the session, 26.5 psi and I was able to run fast laps for 30 minutes.
It took a number of sessions to get there.

Just curious, when you track guys are recommending these pressure figures are you going by the number the TPMS gives you in the iDrive screen or are these numbers from an actual tire gauge? I’ve noticed the car gives ~2psi lower readings than the gauge I use..

[SYT_Shadow]

Originally Posted by MyNameIsNotSure

Just curious, when you track guys are recommending these pressure figures are you going by the number the TPMS gives you in the iDrive screen or are these numbers from an actual tire gauge? I’ve noticed the car gives ~2psi lower readings than the gauge I use..

Tpms is disabled in mine. I use a proper gauge

[jmg]

Originally Posted by MyNameIsNotSure

Just curious, when you track guys are recommending these pressure figures are you going by the number the TPMS gives you in the iDrive screen or are these numbers from an actual tire gauge? I’ve noticed the car gives ~2psi lower readings than the gauge I use..

TPMS is good for checking if you are severely over or under, but is not a substitute for a gauge.

It saved me once when mid-lap my rear passenger side was suddenly low. At first I hadn't noticed because I had a passenger at the time and dismissed the less than ideal rear end squirminess due to the added weight. It was enough, however, to make my check the TPMS. I pulled into the pits and found my rear had de-beaded. In this case TPMS saved at least my tire and rim from potential obliteration. It might have even saved the car from an accident or worse, injury to myself, my passenger, or another driver.