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Old 07-13-2009, 11:01 PM   #1
KUEDA
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Default Track Tire Pressure Re01R's

Hey I'm running 245/40/17 Re01R's on my 2007 STi, I was just wondering what the best tire pressure to run would be. My local track is short and tight, lap times around 70 seconds. Last time I ran 43 psi (hot) in the front and 38 psi (hot) in the rear. Is that a good pressure or too much?
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Last edited by KUEDA; 07-13-2009 at 11:27 PM.
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Old 07-13-2009, 11:07 PM   #2
vinceGC8
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not sure if mine are thee right pressures. but usually when i hit the track, my pressures are around 35F and 36R.
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Old 07-14-2009, 02:25 PM   #3
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When I had my 2005 STi on 255/40/17 RE01R's I ran 37.5F / 35R tire pressures cold. Gave me good balance and quick lap times.
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Old 07-14-2009, 05:43 PM   #4
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Quote:
Originally Posted by import111 View Post
When I had my 2005 STi on 255/40/17 RE01R's I ran 37.5F / 35R tire pressures cold. Gave me good balance and quick lap times.
is that for autox or on a road course.

those are really high cold pressures.
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Old 07-15-2009, 01:21 AM   #5
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Quote:
Originally Posted by vinceGC8 View Post
is that for autox or on a road course.

those are really high cold pressures.
Road course. I chalked up the sidewalls to see how they react and at those pressures everything was perfect at the end of every session. Flat contact patch without rolling over at all.
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Old 07-15-2009, 02:54 PM   #6
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An easy way to see if your tires pressures are too high is to go out, try to drive consistently, and time yourself.

If your lap times are faster at the beginning of the session then steadily fall off your tire pressures are too high. i.e. Tires get hot early then get too hot and fall off in performance.

Visa Versa, If you are slow at the beginning of the session and then steadily get faster you need more tire pressure because it takes too long for the tires to get hot (not too hot though).
It is really a balance.
This is a easy way to check if you can drive consistently...
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Old 07-15-2009, 11:16 PM   #7
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Quote:
Originally Posted by vinceGC8 View Post
is that for autox or on a road course. those are really high cold pressures.
Based on what? It's within .5-psi of what I use in general for my 255/40 RE01Rs on 17x8.5 wheels for autox (and what I'd use for track as well).

And to the OP, your hot psi seems like they're probably in the ball park. Too many un-named variables (suspension, wheel width, available camber, etc.) to give you a definitive answer, though--how does the car feel to you at those pressures?

Bottom line, though, is if this is for "fun" it doesn't really matter as long as the car seems well balanced to you. If you really want to set them properly get a tire pyrometer and check temps across the tread after repeated sessions, or better yet on a test skidpad.
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Old 07-15-2009, 11:30 PM   #8
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Originally Posted by gregr01 View Post
Based on what? It's within .5-psi of what I use in general for my 255/40 RE01Rs on 17x8.5 wheels for autox (and what I'd use for track as well).
so what are your pressures after you warm the tires up and get some heat in them? i cant imagine them being in the low or even mid 40s at the track once you warm them up and really drive on them.

for autox i can understand since by the end of a 60 second or so run, the tires dont build up too much pressure and heat.
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Old 07-16-2009, 09:08 AM   #9
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Stock apparently on my 04 STi is 36/30 so I tried 38/33 today to give me more of a stock-like front to back split. Not sure how much I like it... 255/40/17 on 17x8.5 +48 RE01R
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Old 07-16-2009, 11:11 AM   #10
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Quote:
Originally Posted by vinceGC8 View Post
so what are your pressures after you warm the tires up and get some heat in them? i cant imagine them being in the low or even mid 40s at the track once you warm them up and really drive on them.

for autox i can understand since by the end of a 60 second or so run, the tires dont build up too much pressure and heat.
Good point. I keep my autox pressure stable from run-to-run by reducing psi between runs, starting at 37/35.

Track (HPDE "for fun" though open passing group) it'll go up at least 5psi, and looking at my past data I would end up going out closer to 32/30 f/r "cold" though that's a relative term in AZ.

You're right, and thanks for the reminder... I hadn't looked at my data in a while (too much time chasing cones lately).
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Old 07-16-2009, 05:35 PM   #11
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I wouldn't recommend 32psi in the front on an STi anytime. Stock recommendation is 36. Especially on a wider tire.
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Old 07-16-2009, 09:09 PM   #12
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I run 45 cold up front, 42 cold in the rear on my WRX for most events, but I'm not using the RE01R's.

You will get a lot of input regarding your question, but the truest answer you will receive is going to come from a pyrometer, at the event. If you have your alignment completely dialed in, and you are searching for a tire pressure that will work, the equipment will help you. Adjusting tire pressures should be used to fine tune an already sorted system, using pressure adjustment as a "main" adjustment only compromises the handling. Masking the flaws of a poorly setup system with tire pressure changes is a very common mistake (not saying that is what you are doing, just stating an observation I have made over the years). Did you use a pyrometer to find the sweet spot for your tires insofar as camber ?
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