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Old 05-05-2009, 09:33 PM   #1
hklatte
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Default Tire Pressure for AutoX

I just started doing AutoX and I'd been running with Nitto NeoGen 215/45/17 with 40 psi front and 36 psi rear. It worked fairly well to me, but in the end they were just some used-up all weather tires that kept me from going too fast into the corners.

So now I've just got myself a new set of Falken Azenis R-615 225/45/17 dedicated for AutoX. Does anyone have experience on what tire pressures to use on these tires?
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Old 05-05-2009, 09:46 PM   #2
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Pressures will vary depending on your suspension setup. 40/36 is a place to start, mark the tires and work your way down. I think I ran 36/33 with RT615s on a stockish suspension.
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Old 05-05-2009, 10:54 PM   #3
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Originally Posted by mla163 View Post
Pressures will vary depending on your suspension setup. 40/36 is a place to start, mark the tires and work your way down. I think I ran 36/33 with RT615s on a stockish suspension.
Thanks for the quick reply!

36/33 on stock suspension, huh... I originally thought I had to go up, but well...

I have STI pinks springs (f223/r195) and STI 20mm rear sway bar. Stock shocks and wheels. Is it stockish like yours?
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Old 05-06-2009, 09:05 AM   #4
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I had more bar and lots of camber. Again, individual results may vary. Get some shoe polish and mark the shoulders of the tires, adjust from there.
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Old 05-06-2009, 12:45 PM   #5
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Quote:
Originally Posted by mla163 View Post
I had more bar and lots of camber. Again, individual results may vary. Get some shoe polish and mark the shoulders of the tires, adjust from there.
At least I know where to start tuning the pressure now. Thanks a lot
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Old 05-11-2009, 11:57 AM   #6
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not to thread jack but i figured itd be easier posting in this thread than making a whole nother thread for the same question

im running 205/55/16's on my car and i have coilovers, what tire pressures you think i could gain a little more out of my autocrossing with?
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Old 05-11-2009, 03:02 PM   #7
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Originally Posted by bugeye-joemomma View Post
not to thread jack but i figured itd be easier posting in this thread than making a whole nother thread for the same question

im running 205/55/16's on my car and i have coilovers, what tire pressures you think i could gain a little more out of my autocrossing with?
No problem, man. I think it's good to post out the tire pressures vs setups so everyone can have something to shoot for.

Do you mine telling what kind of tires you are running?
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Old 05-11-2009, 03:09 PM   #8
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Okay, here is what I got from the autox day last Saturday:

Suspension Setups:
STI pinks springs (f223/r195), STI 20mm rear sway bar and Perrin front and rear endlinks. Stock shocks and wheels. OEM otherwise. Camber -1.1F -1.5R.

Tires & Pressure:
Falken Azenis RT615 225/45/17 (there are tiny triangles near the end of the tread. The "perfect" pressure should be when the road contact is exactly the tip of the triangle.

For the front, I put 43 psi (cooled off in a 103 F day...) and it went up to the first line. But since it is still below the triangle, I should have put in more pressure... well... next time...

In the rears, I had 33 psi (cold, again in a 103 F day). I could have reduced 1 or 2 psi more since it never got below the tip of the triangles.

Results:
Overall I was pretty happy about the new tires and pressure settings, but I still had some understeering. Next time I'll increase the tire pressure in the fronts to prevent rubbing over to the side wall and reduce the pressure in the rears to promote a little more oversteering.

Last edited by hklatte; 05-11-2009 at 03:17 PM.
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Old 05-11-2009, 03:11 PM   #9
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different tires are going to require different pressures as well.

i found running 42 front, 45 rear gave me decent grip in bridgestone potenza re-01rs. when i dropped the front some more i felt the rolled over a bit too much. but at the point i might have been being a bit heavy on the right foot.

im running again at the end of may, ill probably do my first run at 45/45 and adjust from there.
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Old 05-11-2009, 03:12 PM   #10
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Quote:
Originally Posted by hklatte View Post
Okay, here is what I got from the autox day last Saturday:

Suspension Setups:
STI pinks springs (f223/r195), STI 20mm rear sway bar and Perrin front and rear endlinks. Stock shocks and wheels. OEM otherwise.

Tires & Pressure:
Falken Azenis RT615 225/45/17 (there are tiny triangles near the end of the tread. The "perfect" pressure should be when the road contact is exactly the tip of the triangle.

For the front, I put 43 psi (cooled off in a 103 F day...) and it went up to the first line. But since it is still below the triangle, I should have put in more pressure... well... next time...

In the rears, I had 33 psi (cold, again in a 103 F day). I could have reduced 1 or 2 psi more since it never got below the tip of the triangles.

how did that fair for getting the rear end around? i found running a smaller contact patch in the rear made for the rear "feel" a bit loose and quick.
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Old 05-11-2009, 05:19 PM   #11
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Quote:
Originally Posted by hklatte View Post
No problem, man. I think it's good to post out the tire pressures vs setups so everyone can have something to shoot for.

Do you mine telling what kind of tires you are running?
right now im on some michelin MXV4's lol crappy all seasons but i dont have money for good tires right now
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Old 05-11-2009, 05:19 PM   #12
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45 rear? omfg !

Better Grip (ie more traction and lower times) or quicker steering response / less snap over steer? When i ran a 255/40/17 615 I noticed they "felt" Gripper at like 45 front, and had Much better steering response, but the car was "faster" with less psi. tire chalking and a day with 12 runs on a 60 second course. let me figure that out ..

I've found that low rear tire pressure can give you transitional oversteer (snap oversteer) but seem to provide better grip.

I ran the 615 and the RE01R (last 2 seasons) i seemed to always find that
40 / 36 gave the best traction (lowest times) stock STI , 29 Front sway. -1 camber / -2 rear.

With more camber or less body roll i would probably run lower PSI, my car wants more camber (pyrometer readings) but i can't (stock class) so i use higher pressure.
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Old 05-11-2009, 06:46 PM   #13
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Quote:
Originally Posted by A1337STI View Post
45 rear? omfg !

Better Grip (ie more traction and lower times) or quicker steering response / less snap over steer? When i ran a 255/40/17 615 I noticed they "felt" Gripper at like 45 front, and had Much better steering response, but the car was "faster" with less psi. tire chalking and a day with 12 runs on a 60 second course. let me figure that out ..

I've found that low rear tire pressure can give you transitional oversteer (snap oversteer) but seem to provide better grip.

I ran the 615 and the RE01R (last 2 seasons) i seemed to always find that
40 / 36 gave the best traction (lowest times) stock STI , 29 Front sway. -1 camber / -2 rear.

With more camber or less body roll i would probably run lower PSI, my car wants more camber (pyrometer readings) but i can't (stock class) so i use higher pressure.
^+1 on a bigger front sway bar + lower psi. I was thinking that for my next upgrade too. But whiteline only makes 22 mm front sway bar for wagons. Wondered if perrin will fit...

I thought stock class allowed bigger front sway bar...
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Old 05-12-2009, 12:30 AM   #14
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Quote:
Originally Posted by hklatte View Post
^+1 on a bigger front sway bar + lower psi. I was thinking that for my next upgrade too. But whiteline only makes 22 mm front sway bar for wagons. Wondered if perrin will fit...

I thought stock class allowed bigger front sway bar...
Front sway bar is free in the stock class. Rear sway bar is verboten to change.

I have a 7/8" front bar and run 42/38 psi on the RE070's. I am thinking about going up to a 1", or 29mm front bar.
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Old 05-12-2009, 11:15 AM   #15
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Quote:
Originally Posted by bugeye-joemomma View Post
not to thread jack but i figured itd be easier posting in this thread than making a whole nother thread for the same question

im running 205/55/16's on my car and i have coilovers, what tire pressures you think i could gain a little more out of my autocrossing with?
Quote:
Originally Posted by bugeye-joemomma View Post
right now im on some michelin MXV4's lol crappy all seasons but i dont have money for good tires right now
but for some help please, im a hardcore n00b at this
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Old 05-12-2009, 11:32 AM   #16
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I continue to mess with pressures at each event, just keep trying new things.

i also find the re01rs dont heat up like i expect them too. my tire pyrometer readings are usually only slightly higher then ambient. what temps do street tires usually get to on a 60 sec course?
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Old 05-13-2009, 10:22 AM   #17
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on the falkens l like 36 front and 34 on the back. Depending on weather i will drop the back to 33-32.
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Old 05-13-2009, 11:31 AM   #18
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on the falkens l like 36 front and 34 on the back. Depending on weather i will drop the back to 33-32.
My falkens in the front rolled over to the side wall a little even with 43 psi. How big a front sway bar do you have? What spring/coilover do you have? What should I do to use a lower psi while not rolling over to the side wall? More negative camber? Bigger front sway bar?
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Old 05-14-2009, 01:39 PM   #19
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Quote:
Originally Posted by hklatte View Post
^+1 on a bigger front sway bar + lower psi. I was thinking that for my next upgrade too. But whiteline only makes 22 mm front sway bar for wagons. Wondered if perrin will fit...

I thought stock class allowed bigger front sway bar...
All you have to do to get the bigger front bars to fit the Wagon is use spherical end links.
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Old 05-14-2009, 04:03 PM   #20
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All you have to do to get the bigger front bars to fit the Wagon is use spherical end links.
That's perfect. I have Perrin end links.

Thanks!
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Old 05-15-2009, 09:45 AM   #21
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I believe that using tire pressure to fine tune a setup is very useful. However trying to use tire pressure to compensate for a poor setup is not. Example: I did an event with a baseline alignment of -1.8 f, -1.1r, 0.00 toe all 4. If I tried to use tire pressure to get off the edge of the tire, it would not be the best solution just yet. I switch to -2.5 f, -1.5 rear, 0.00 toe all 4. Much better. I might be better served with -3.0 f, -2.0 r. I was at 40 psi all around as I was not focusing on pressure just yet. Once I get the camber dialed in so that the tires are actually using the maximum tread, I can then focus on what the car is actually doing in a corner, and how can I make it better. If the anti-roll bars, strut settings, spring rate, alignment, and driver technique are optimum adjusting tire pressure will help more than it hurts.
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Old 05-15-2009, 09:53 AM   #22
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I believe that using tire pressure to fine tune a setup is very useful. However trying to use tire pressure to compensate for a poor setup is not. Example: I did an event with a baseline alignment of -1.8 f, -1.1r, 0.00 toe all 4. If I tried to use tire pressure to get off the edge of the tire, it would not be the best solution just yet. I switch to -2.5 f, -1.5 rear, 0.00 toe all 4. Much better. I might be better served with -3.0 f, -2.0 r. I was at 40 psi all around as I was not focusing on pressure just yet. Once I get the camber dialed in so that the tires are actually using the maximum tread, I can then focus on what the car is actually doing in a corner, and how can I make it better. If the anti-roll bars, strut settings, spring rate, alignment, and driver technique are optimum adjusting tire pressure will help more than it hurts.
I see. That's some very helpful info.

Do you have camber plates or do you use camber bolts? I asked this question in another thread, but no one seem to know the answer: will there still be enough clearance between the struts and 225/45/17 tires to dial in -2.5 to -3 deg of camber in the front with extra camber bolts for wagons?
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Old 05-15-2009, 10:32 AM   #23
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Quote:
Originally Posted by hklatte View Post
I just started doing AutoX and I'd been running with Nitto NeoGen 215/45/17 with 40 psi front and 36 psi rear. It worked fairly well to me, but in the end they were just some used-up all weather tires that kept me from going too fast into the corners.

So now I've just got myself a new set of Falken Azenis R-615 225/45/17 dedicated for AutoX. Does anyone have experience on what tire pressures to use on these tires?
mods:
koni shocks
RCE wagon springs
Group N tops
whiteline sways 22/22
kartboy endlinks f/r
strut tower braces f/r

I run the falkens in the same size and have found with this setup 36/36 seems to work best as a cold temperature to start with. Your results may vary though depending on your mods, driving style, and course.
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Old 05-15-2009, 10:52 AM   #24
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Quote:
Originally Posted by hklatte View Post
I see. That's some very helpful info.

Do you have camber plates or do you use camber bolts? I asked this question in another thread, but no one seem to know the answer: will there still be enough clearance between the struts and 225/45/17 tires to dial in -2.5 to -3 deg of camber in the front with extra camber bolts for wagons?
I don't use camber plates because I don't want to jack my SAI around, it's one of the geometry advantages we have with the wagon. I have aftermarket camber bolts in the front lower and rear upper strut mounting holes. I have enough room on stock strut bodies to run -3.0 and use 245's. I took the 225-45-17's off and went to 215's again. The tires I am running are wider at 215 than the 225's were anyway. I am ordering my 17x8.5's very soon though, now that I know it all works.
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Old 05-15-2009, 11:23 AM   #25
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I don't use camber plates because I don't want to jack my SAI around, it's one of the geometry advantages we have with the wagon. I have aftermarket camber bolts in the front lower and rear upper strut mounting holes. I have enough room on stock strut bodies to run -3.0 and use 245's. I took the 225-45-17's off and went to 215's again. The tires I am running are wider at 215 than the 225's were anyway. I am ordering my 17x8.5's very soon though, now that I know it all works.
wow... really? Which tire is that? Would you mind letting us know?

Sorry for a noob questions... but what is SAI? Where could I read more about the geometry advantages in the wagons?
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