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Tire Pressure Help!!!

MattMiles44

Premium Member
Name
Matthew Miles
Joined
Aug 29, 2018
Messages
53
Age
27
Location
USA, Colorado, Colorado Springs
iRacing ID
325269
Hey guys. I'm still totally lost when it comes to setting up tire pressure. The chassis I'm alright with, I have a pretty good understanding of spring rate and cambers. It's tire pressures where I'm lost.

I understand that low pressure means more grip and more heat buildup, and high pressure means less grip and less heat buildup. But I get confused when the track temp changes. I run 22 PSI all around, after about 8-10 laps I see temps reach 200-210 F (outer 170 F) and the rear reaches nearly 230 F on a 100 F - 105 F track. I've moved the PSI around, did 20 PSI in the front and 24 in the rear. Same amount of laps and same track temp, got the same pressures. 

Am I not doing enough laps for accurate data? Also, what tire temp should I be aiming for? I'm not asking for everyone's tire pressures, I understand it really depends on many different factors. As a moto guy, tire pressures are much different (obviously) and i'm just having issues understanding what I'm looking for when testing tire pressures and what temps I should be aiming for.

Last question, if a track cools down from 105 F to 90 F, should I lower pressure or raise pressure?

All answers or links are appreciated. I lowered tire pressures for Watkins Glen and it dropped almost a full second for my pace, but I haven't the slightest clue why that was  :oops: :cry:
 
Thanks guys  :mrgreen:
 

DeamingPie

Premium Member
Ferrari Challenge Fixed 2022/S2
Name
Erik Luke
Joined
Jan 8, 2018
Messages
612
Location
Florida
iRacing ID
308605
While I cannot answer the tire dynamics that iRacing uses, I can tell you all last season my pressures were set at 19 PSI all around, and it hasn't changed at all this season. I have noticed that if you set the PSI higher, the operating temp of the tire will come up quicker but grip will suffer mid race.

Don't take this as gospel, but it seems that the lower the PSI the lower the tire temps will be, even though you are creating more of a contact patch. The only race I ran into severe grip problems was Tsukuba. This could also be a cause of running too high camber as well.
 

Rem Ambruosi

Well-known member
Name
Joined
Feb 15, 2019
Messages
103
Location
Australia
Hi , I feel out the track, and as its afternoon for Rd Atlanta, it was morning for Watkins, so i will pick a few psi levels.and after a few prac runs, I will pick the best, even if the best is still a little loose, then I don't change it for prac, qualify or the race. 

When one psi setting is good at lets say 70-80F, we all know it might not be so great at 90-100F, you need to pick a psi that your comfortable with for the time of day, as you cannot go into the pits and keep changing psi every time it jumps up by 10F if your racing.
Its a hard call, doing at least 10 prac laps per psi set ups takes time, but its time worth doing.
I like running the same psi all round.
 

TRG

Director
Staff member
Formula 3 Series 2022/S2
Name
Tyler Gore
Joined
Feb 11, 2017
Messages
3,399
Age
38
Location
Saskatoon, SK, Canada
iRacing ID
194814
When you say you pick the best pressure, how does one decide what the best is?
 

Rem Ambruosi

Well-known member
Name
Joined
Feb 15, 2019
Messages
103
Location
Australia
TRG said:
When you say you pick the best pressure, how does one decide what the best is?

Testing, Testing , Testing  ,and its all about how it feels for the individual driver, Erik says he uses 19psi, it works for him, but that might not be any good for you, I don't use 19psi
I really go by what time of the day it is, in my view air temps also play a part in deciding pressures, so its all about testing in the same condition as race conditions , usually pressures between the 19psi-22psi, I feel anything under or over is a bit of a waste of time, but  hey that's just my opinion.
I use a different psi for morning, afternoon , late afternoon and night, mostly due to different air temps.
 

TRG

Director
Staff member
Formula 3 Series 2022/S2
Name
Tyler Gore
Joined
Feb 11, 2017
Messages
3,399
Age
38
Location
Saskatoon, SK, Canada
iRacing ID
194814
Makes sense. Thanks Rem.

I was curious if there was any analytical way to sort it out based on hot pressures, temps, or other telemetry. Scientific methods are always easier in my mind.
 

Rem Ambruosi

Well-known member
Name
Joined
Feb 15, 2019
Messages
103
Location
Australia
TRG said:
Makes sense. Thanks Rem.

I was curious if there was any analytical way to sort it out based on hot pressures, temps, or other telemetry. Scientific methods are always easier in my mind.
I'm on the other end of the scale, I use the KISS method  (Keep It Simple Stupid) lol
 

TheGreatC81

Premium Member
Ferrari Challenge Fixed 2022/S2
Name
David Cristelli
Joined
Nov 15, 2017
Messages
322
Location
USA, CT, Enfield
iRacing ID
321605
Ok, I'm confused. I was told several times that until the new tire model comes out, we should run the lowest pressure we can. Is that not the case with the Radical? I'm used to GT cars.
I usually look for an operating pressure of around 21.5 psi. To get there I have the Radical at 16-16.5 psi all around. It takes a couple laps to get up to temp and pressure, but once there it feels pretty good. (To me anyway, but what do I know?) 
 
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