Welcome to the North American Subaru Impreza Owners Club Thursday April 17, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
Click here to visit TireRack
Tire & Wheel Forum sponsored by The Tire Rack

Losing traction? Need new tires?
Click here to visit the NASIOC Upgrade Garage...
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Tire & Wheel

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads.
Reply
 
Thread Tools Display Modes
Old 07-09-2004, 01:25 PM   #1
Jeff_DML
Scooby Specialist
 
Member#: 32018
Join Date: Jan 2003
Chapter/Region: SCIC
Location: San Diego, CA.
Vehicle:
2008 M3 Sedan
Interlagos Blue

Default tire pressure suggestions for auto-x

I am running Kumho MX 225/45 on 17x7 rims. I am used to running my tires in the upper 30s psi but at my last auto-x some STi guys where running in the upper 40s which seems high to me. Any suggestion on what pressure I should run for auto-x? Not so much exact pressure but general range.

thanks
* Registered users of the site do not see these ads.
Jeff_DML is offline   Reply With Quote
Old 07-09-2004, 01:35 PM   #2
NeoteriX
Scooby Specialist
 
Member#: 20999
Join Date: Jul 2002
Chapter/Region: NESIC
Location: NJ
Vehicle:
2002 PSM WRX Stg 2
knee - Aw - teh - rix

Default

I run like 45.5 on my 225/16-50 Yoko ES100s. Street tires need a little more for the autox...

But why don't you figure out what works best for you? Buy some white show polish and dab a little on the shoulders of your tires. My ES100s have little triangles on the shoulder of the tire indicating where the shoulder ends and where the wear should be -- I dab some shoe polish right onto the triangles.

Check where the shoe polish is worn away -- if its right to the tip of the triangle, you're all set. Get a tire pressure reading and that should be the point by which you can make further slight adjustments. If the whole mark is work out, more pressure, if the wear doesn't get to the triangle, less.
NeoteriX is offline   Reply With Quote
Old 07-09-2004, 01:39 PM   #3
Jeff_DML
Scooby Specialist
 
Member#: 32018
Join Date: Jan 2003
Chapter/Region: SCIC
Location: San Diego, CA.
Vehicle:
2008 M3 Sedan
Interlagos Blue

Default

Quote:
Originally posted by NeoteriX
I run like 45.5 on my 225/16-50 Yoko ES100s. Street tires need a little more for the autox...

But why don't you figure out what works best for you? Buy some white show polish and dab a little on the shoulders of your tires. My ES100s have little triangles on the shoulder of the tire indicating where the shoulder ends and where the wear should be -- I dab some shoe polish right onto the triangles.

Check where the shoe polish is worn away -- if its right to the tip of the triangle, you're all set. Get a tire pressure reading and that should be the point by which you can make further slight adjustments. If the whole mark is work out, more pressure, if the wear doesn't get to the triangle, less.
thanks I was planning on doing that but my original pressure assumption was so far off from the STi guys I wanted to know where to start. Mid 40s seems to be the place.

thanks
Jeff_DML is offline   Reply With Quote
Old 07-09-2004, 02:50 PM   #4
Scooby Freak
Scooby Specialist
 
Member#: 40751
Join Date: Jul 2003
Chapter/Region: Tri-State
Location: Springfield
Vehicle:
'94 SER

Default

I would start w/ the max pressure that is allowed according to the sidewall, usually 51 or 44. Then work down from there. I do that because it's easier to release pressure, then to add it.

I don't know what sort of suspension you are on, but for my stock suspension, the car feels better with more pressure in the rear.
Scooby Freak is offline   Reply With Quote
Old 07-09-2004, 02:58 PM   #5
Jeff_DML
Scooby Specialist
 
Member#: 32018
Join Date: Jan 2003
Chapter/Region: SCIC
Location: San Diego, CA.
Vehicle:
2008 M3 Sedan
Interlagos Blue

Default

Quote:
Originally posted by Scooby Freak
I would start w/ the max pressure that is allowed according to the sidewall, usually 51 or 44. Then work down from there. I do that because it's easier to release pressure, then to add it.

I don't know what sort of suspension you are on, but for my stock suspension, the car feels better with more pressure in the rear.
But I thought pressure increases when your tires get hot so figure it might be dangerous going that route

I am running JDM V8 Sti takeoffs
Jeff_DML is offline   Reply With Quote
Old 07-09-2004, 04:39 PM   #6
NeoteriX
Scooby Specialist
 
Member#: 20999
Join Date: Jul 2002
Chapter/Region: NESIC
Location: NJ
Vehicle:
2002 PSM WRX Stg 2
knee - Aw - teh - rix

Default

Quote:
Originally posted by Jeff_DML
But I thought pressure increases when your tires get hot so figure it might be dangerous going that route

I am running JDM V8 Sti takeoffs
afpdl, an experienced autocrosser round these here parts, was telling me how he had 60+ psi in the stock RE-92s, in an attempt to stop the aweful rollover. They didn't explode or anything.

Where are you inflating your tires? At the SCCA autox here in Houston, they have compressed air on the premises, and in either case, I have my own 12v air compressor -- you might wanna look into getting one - it's like $10-$20 at Walmart. It's loud as hell and takes forever to put air in your tires, but it's a relatively inexpensive solution to fiddling around with air pressures at an autox.

In this case, the tires are warmed up a bit from driving to the autox. They say that warm tires vs. cold add about 4.5 psi, so starting at like 45-50 warm and working down shouldn't be much beyond tire spec.
NeoteriX is offline   Reply With Quote
Old 07-09-2004, 04:44 PM   #7
Jeff_DML
Scooby Specialist
 
Member#: 32018
Join Date: Jan 2003
Chapter/Region: SCIC
Location: San Diego, CA.
Vehicle:
2008 M3 Sedan
Interlagos Blue

Default

Quote:
Originally posted by NeoteriX
afpdl, an experienced autocrosser round these here parts, was telling me how he had 60+ psi in the stock RE-92s, in an attempt to stop the aweful rollover. They didn't explode or anything.

Where are you inflating your tires? At the SCCA autox here in Houston, they have compressed air on the premises, and in either case, I have my own 12v air compressor -- you might wanna look into getting one - it's like $10-$20 at Walmart. It's loud as hell and takes forever to put air in your tires, but it's a relatively inexpensive solution to fiddling around with air pressures at an autox.

In this case, the tires are warmed up a bit from driving to the autox. They say that warm tires vs. cold add about 4.5 psi, so starting at like 45-50 warm and working down shouldn't be much beyond tire spec.
yeah I got one of those, going to start at 45 and go from there. I think 50 is my max rating.
Jeff_DML is offline   Reply With Quote
Old 07-09-2004, 07:39 PM   #8
NeoteriX
Scooby Specialist
 
Member#: 20999
Join Date: Jul 2002
Chapter/Region: NESIC
Location: NJ
Vehicle:
2002 PSM WRX Stg 2
knee - Aw - teh - rix

Default

Quote:
Originally posted by Jeff_DML
yeah I got one of those, going to start at 45 and go from there. I think 50 is my max rating.
BTW the max rating listed on the tire should be max cold pressure, so once your tires are warmed up, you could still have a guilt free conscience pumping the pressures up to 55ish.
NeoteriX is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Tire pressure suggestions. Jeff8407 Tire & Wheel 0 06-27-2009 06:47 PM
car suggestions for auto x stealthWRX68 Motorsports 7 08-02-2008 09:54 PM
Sumitomo HTR+ tire pressure suggestions? filter27e Tire & Wheel 1 10-26-2006 08:00 AM
Tire Pressure suggestion V6 Brakes, Steering & Suspension 2 03-10-2003 08:06 AM
Psi suggestions for auto-x w/Kumho 712's? Opie Technical Forum Archive 4 09-13-2000 07:24 PM


All times are GMT -4. The time now is 05:49 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.