[Chewyc]

Hello friends, tomorrow will be my first Solo II event. I was wonder what is the pressure setting for the front and back stock Potenza tires. The car is complete stock by the way, and is there any quick pointer for a novice? Anything will be greatly appreciate.

[Xman]

see if you can find an instructor to help you out. Also do a search for the autoX informational threads. One used to be a sticky.

Start with about 46psi front and rear and air them down as they heat up during the day and as you optimize contact patch. If it's your first event concentrate most on learning the course and finding the fast line. Remember, slow in fast out.

Have fun!!

[wrxtc]

My first event was last week. On my stock Potenza RE070 tires I ran 42psi front and 40psi rear with no sidewall rolling (I marked them with some shoe polish). However, these tire pressures went up to like 45-47psi once the tires got hot.

I only had to drive about 2 minutes from my house to the race venue so my tires were still quite cold when I inflated them.

[scottWRX]

I ran my first event this past Sunday and ended up with 44psi front and 40psi rear. The STi seemed to like those settings.

Scott

[felonious]

I run mine at 40/40 cold and just let them heat up as I go. Maybe not the best, but that's what I do.

-Ollie

[WRXRATED7]

I've been using 42 F/44 R with success. The reason I use more pressure in the rear is to create a little more oversteer. I just like the way it feels racing it like that.

[Turninconcepts.com]

I have had great success with 44/40.

[Digitalfiend]

I just came back from my first autoX event (school actually...but with timing equipment ) and all the instructors recommended less in the rear. Every Subaru there ran less pressure in the rears, which apparently makes them looser. It certainly helped me. I always thought that running more pressure in the rear helped with oversteer, but apparently that works better with Hondas.

Anyhow, the first day they made all the newbies run 45psi around but by the second day they were telling the Subie drivers to drop the pressure to about 36-38psi. Let me tell you that made a world of difference. I went from pushing heavily in some corners to getting mild but controllable oversteer...and I only dropped to 40psi. Another STi driver, Dean, was running lower pressure (36 or something like that) and coupled with some nice driving, was running pretty fast.

[AuroraSTi]

I run 46/42 with both stock sway bar and a Perrin sway bar at 22mm. This Sun. I will run it at 24mm if it doesn't snow too bad. Snow in May....gotta love CO

[jermdeez]

dude 46 psi is insane....

are sti's special for tire pressure

Because running that much in a 17 inch tire is not right normally.

You want to have like between 33-36, 40's is ridiculous and seems like it'd only hurt handling. Esepcially with how stiff the sidewalls are already.

[AuroraSTi]

You would think that high press. would be bad, but I found it works pretty good for me. I air them down as they heat up though. When I ran stock pressure, I rolled about half way down the sidewall. Could be the super grippy concrete at DIA.

[Digitalfiend]

Originally Posted by jermdeez

You want to have like between 33-36, 40's is ridiculous and seems like it'd only hurt handling. Esepcially with how stiff the sidewalls are already.

33-36 in the front? For autox? Man I was nearing the roll over mark at 43psi in the front...

[WRXRATED7]

Originally Posted by jermdeez

You want to have like between 33-36, 40's is ridiculous and seems like it'd only hurt handling. Esepcially with how stiff the sidewalls are already.

You sound like you've never AutoX'd before. I can see 36 or so if you're on a roadcourse, but for AutoX I will usually run close to max pressure depending on how much grip I'm getting.

[WRX_Mundi]

33 in front is, in my opinion, far too low. The STi is heavy and also front heavy. It would be terrible for novices especially as they tend to go into corners too fast which will really roll the fronts over.

I seem to run lower pressures than a lot of people I see post here. But I've looked at both rollover and used an insertion pyrometer, getting good wear marks and even temperatures with -2.8 camber and 39psi front and 36 rear. This is asphalt. On concrete I could see going a bit more -- 40 to 42. I could see 37-38 front if the lot was very slippery. As usual these are hot temperatures. We usually get 6-8 runs a day so I tend to not worry excessively about initial settings, setting it to a couple pounds less for the first run, then releasing pressure to get the desired setting after each run (after three runs it usually doesn't need any more change).

My philosophy is to set the fronts to the "correct" value which you can examine via pyrometer, rollover, or if you're very good or have a big ego, feel. On a road course the correct answer is always pyrometer, but autocross makes that a bit harder to determine. Next, I set the rear pressures to make the car balance the way I want (this was before I had control of shock settings). Now if the pressures are goofy or the pyrometer reading says they're wrong, then I'll see about alignment changes for next time, since I'm not able to adjust camber or toe at an event. Adjustable rear swaybars can help too.

[sciolist]

Originally Posted by WRX_Mundi

My philosophy is to set the fronts to the "correct" value which you can examine via pyrometer, rollover, or if you're very good or have a big ego, feel. On a road course the correct answer is always pyrometer, but autocross makes that a bit harder to determine. Next, I set the rear pressures to make the car balance the way I want (this was before I had control of shock settings). Now if the pressures are goofy or the pyrometer reading says they're wrong, then I'll see about alignment changes for next time, since I'm not able to adjust camber or toe at an event. Adjustable rear swaybars can help too.

Oh great, now I have a big ego as well as an inferior tool box.

Seriously, 40psi is a good cold starting point for all four corners. Take a run and note how much pressure is gained. You will probably be airing the tires down between runs.

Most people run a little less pressure in the rears on these cars to balance the steer characteristics, but that tends to sacrifice grip. For any car/tire/course combination there is an ideal pressure in terms of grip. This is the pressure you want, if you want to maximize grip.

It’s generally easier to tune the steer characteristics by manipulating pressure, but you get more traction if you tune by manipulating suspension settings. If you want your car to rotate more, and you can change suspension settings, then do that – and set the tire pressures for maximum traction based on observation and pyrometer readings.

If you cannot manipulate suspension settings, then it’s probably best to give up some grip in the name of handling, but that’s a trade-off that needs to be carefully balanced.