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Old 05-04-2001, 05:09 PM   #1
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Join Date: Mar 2001
Chapter/Region: BAIC
Location: detailaddict.com

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Old 05-04-2001, 05:13 PM   #2
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Join Date: Jul 1999
Chapter/Region: MWSOC
Location: Wichita, KS and Whoring, OT
'03 Evo, Rice White
'01 Erion CBR 929


OK, so your car is stock. Including tires?

In that case run max pressure in the front (or more, maybe 50psi) and around 40 in the rear. It won't change the fact that the RE92s suck.

If not, what kind of tires are you using?
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Old 05-04-2001, 05:22 PM   #3
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Location: keeping santa cruz weird
2003 Lancer Evo 8
It's Blue, ok?


The tire presures that will work for you depend on your suspension setup and driving style.

Lets say your maximum rated tire presure is 45psi. You would want to setup your tires with aproximately 40psi all around. If you want more understeer (pushing through the corners) go softer in the rear tires. If you want more oversteer (back end wants to kick out more) then go softer in the front.

Probably the best method to determine what your optimum presures will be is practice practice, and more practice. What you want to do is take white shoe polish or chalk and mark at least 3 points on the circumferance of the tire on the very edge of the tread where it meets the sidewall of the tire.

Ideally you want a tire presure that will remove the marks from the tread only! if the chalk marks are completely gone and the sidewall show signs of scrubbing, then your tire presure is too low and your folding the tire onto the sidewall, very bad..

If the chalk marks are still visible on the tread and sidewall, then your presures are too high.

With the proper alignement and tire presures, your tires should not vary more than 2-3psi between all 4 tires after a autox run, assuming a excellent run with no lockups or wheel spin. If you can acheive all that, then you will have found the magical optimum tire presure.
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Old 05-04-2001, 06:24 PM   #4
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i have stock suspension and tires... i had more understeer last time, but i've changed a little in my driving style since the last race and ready to try it out this weekend. thanks for the tips guys!...

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Old 05-04-2001, 06:53 PM   #5
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Chapter/Region: NESIC
Location: Warwick, RI
2004 WRX
2000 SV650


Isn't it if you run more pressure in the front tires you reduce understeer? By increasing the tire pressure you are keeping the sidewalls stiffer, thus less rollover and more tread contact with the ground. I thought this is what I found out after doing a search before I started autcrossing my car around two years ago? I usually run 44F 41R and have good luck. The tires still suck, but checking the sidewalls/tread after a run look like they don't roll over.
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Old 05-05-2001, 01:21 AM   #6
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Post what are good tire pressures for autox?

what should I have for front and rear tire pressures for Autocross? Thanks guys!

BTW, my car is full stock 2001 RS!
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Old 05-05-2001, 05:42 AM   #7
7000 RPM
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Location: Bath, Ohio, USA

Inflation pressure summarized:
1. More pressure = stiffer carcass = more rapid steering response.
2. Less pressure = larger contact patch = more ultimate grip.
3. Less pressure = softer carcass = more roll-under = may reduce grip (compensate with negative camber).

Other factors include operating temperature, shape of contact patch, and balance between tread and carcass stiffness.

For a stock car, I would start moderately high, like 35-ish, but not as high as 50. Experiment and have fun!
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Old 05-05-2001, 08:34 AM   #8
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Chapter/Region: NWIC
Location: Redmond, WA, USA
2008 Forester XT
Steel Gray Metallic


Yes, on everything except the original BFG R1 tire, more pressure at front = less understeer. More pressure at back = more understeer.

Suspension stiffer at the front = more understeer, suspension stiffer at the back, less understeer.

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