[BDL Motorsports]

I soon will be starting to autocross a 2007 STI with Bridgestone RE-01R tires on it and was wondering what tire pressures guys are running.

Ran a Mustang before and just would like some idea's on pressures front and rear to start with.


Brian

[snorky]

it depends on your suspension setup, alignment, surface quality, tire and rim size, actual tire type, ambient temperature, surface temperature, and driving style, among other things.

I set a cold tire pressure of 33psi in the front and 38psi in the rear and work from there when I get on course. I have -3* camber in the front, -1.5*camber in the rear, 0 toe all around. This is on RE070s. My suspension mods are in my journal. I run high pressures in the rear to get the rear end to break loose a little easier when I want it to.

If you're running stock alignment, get an alignment and max out the front camber. With the ~-1* front camber that you'll be able to get, I would start around 38psi all around. Throw some shoe polish on the outside shoulders of the tire to gauge how much rollover you're getting. More experienced autoxers (if you're not) will gladly help you out if you ask. Too much rollover, add more air (in at least 2psi increments.) Too little rollover, take some air out. The best way to optimize tire inflation and suspension setup is with a probe type pyrometer.

[BDL Motorsports]

Oh, stock suspension for now.

I have 18 x 8" mags and 245/40/18's RE-01R tires.

I will be deciding in the next month if I am selling my race Mustang for this STI and then will mod the STI a bunch. not doing anythign to the STI until my Mustang sells.


So, just want some pressure tips to start out with. been autocrossing for many years now most of the time top 5 overall so a decent driver ( i guess )


Brian

[IlliniSTi]

Originally Posted by snorky

I set a cold tire pressure of 33psi in the front and 38psi in the rear and work from there when I get on course. I have -3* camber in the front, -1.5*camber in the rear, 0 toe all around. This is on RE070s. My suspension mods are in my journal. I run high pressures in the rear to get the rear end to break loose a little easier when I want it to.

When I was on the 070's I would run 38-40 in the front and anywhere from 32-38 in the rear. I tended to run lower pressure in the rear to get better rotation. You can make the car work either way, you just have to decide if you want to be above or below the tire's optimal pressure for lateral grip.

[ploney]

I would also watch the temperature spread acorss the tire, try to get the middle temperature to be between the outside, usually hottest and the inside, usually coolest. Keep adding pressure if the center temperature is the coldest measurement.

I did this with my new Dunlop Direzza' Z1's and ended up with hot pressures of 45 Front and 48 Rear on my bone stock 08 STI. These were 255-35-18's. Rotated nicely with onty 3 psi differnece front to back.

[calves]

I ran on the stock tires, completely stock suspension, w/ 38 front 40 in the rear. I'm sure your tires will grip a lot better than mine, but had minimal tire roll over up front (had 1.5* camber). Goodluck!

[BDL Motorsports]

Originally Posted by calves

I ran on the stock tires, completely stock suspension, w/ 38 front 40 in the rear. I'm sure your tires will grip a lot better than mine, but had minimal tire roll over up front (had 1.5* camber). Goodluck!

Thanks to all... I have helped many Mustang guys over the years and learning a bit more day to day on the STI

Going from 425 hp RWD Mustang ( on V710's ) to 293 hp AWD STI ( RE-01R's for now ) will be a new experience. I have run the STI at some winter autocross events ( snow on pavement ) and got FTD at my second event but now this will be something new for me.

if the STI becomes my dedicated autocross car will be lowering it and rear sway bar and alignment and what ever else ( V710's or A6's ) . Not really looked into what to do much but heard the 3 things I just said are the main things to do.

Brian

[snorky]

Originally Posted by ploney

I would also watch the temperature spread acorss the tire, try to get the middle temperature to be between the outside, usually hottest and the inside, usually coolest. Keep adding pressure if the center temperature is the coldest measurement.

I did this with my new Dunlop Direzza' Z1's and ended up with hot pressures of 45 Front and 48 Rear on my bone stock 08 STI. These were 255-35-18's. Rotated nicely with onty 3 psi differnece front to back.

the temperature should be even all the way across. if it's hottest on the outside, you need to increase negative camber.

[IlliniSTi]

Originally Posted by BDL Motorsports

Thanks to all... I have helped many Mustang guys over the years and learning a bit more day to day on the STI

Going from 425 hp RWD Mustang ( on V710's ) to 293 hp AWD STI ( RE-01R's for now ) will be a new experience. I have run the STI at some winter autocross events ( snow on pavement ) and got FTD at my second event but now this will be something new for me.

if the STI becomes my dedicated autocross car will be lowering it and rear sway bar and alignment and what ever else ( V710's or A6's ) . Not really looked into what to do much but heard the 3 things I just said are the main things to do.

Brian

What class are you looking at going into? The STi doesn't do too well in stock class, unless it rains. From what you mention doing, it looks like you could go STU or BSP. If all you are going to do is springs, bars, and alignment, I would stick with STU and get some star specs. If you have to spend your money on R-comps, then BSP is probably the place for you.

[snorky]

Originally Posted by BDL Motorsports

Thanks to all... I have helped many Mustang guys over the years and learning a bit more day to day on the STI

Going from 425 hp RWD Mustang ( on V710's ) to 293 hp AWD STI ( RE-01R's for now ) will be a new experience. I have run the STI at some winter autocross events ( snow on pavement ) and got FTD at my second event but now this will be something new for me.

if the STI becomes my dedicated autocross car will be lowering it and rear sway bar and alignment and what ever else ( V710's or A6's ) . Not really looked into what to do much but heard the 3 things I just said are the main things to do.

Brian

believe it or not, front sway is going to help more.

[BDL Motorsports]

Most of the STI's here go into BSP so probably that route.


I always run on R compounds so I will go that route ( once I know what car i will be running )... once you go stickies... no going back.

I am just not ready to go that way this summer.... need to get rid of one car or the other.

Oh, front sway bar.. Ok... I willl be reading more once i am ready to start modifying.

I am +1 or rims now ( 18" ) think I will be in B stock for my "try out the car" and see "what I think" runs.

Brian

[IlliniSTi]

Originally Posted by BDL Motorsports

Most of the STI's here go into BSP so probably that route.


I always run on R compounds so I will go that route ( once I know what car i will be running )... once you go stickies... no going back.

I am just not ready to go that way this summer.... need to get rid of one car or the other.

Oh, front sway bar.. Ok... I willl be reading more once i am ready to start modifying.

I am +1 or rims now ( 18" ) think I will be in B stock for my "try out the car" and see "what I think" runs.

Brian

Front sway is stock legal, but +1 is not. Stock rules require same diameter and width as stock, so 17x8 for 05+, and offset within 1/4" of stock. Not sure how well your region polices the rules, but since it sounds like you finish near the top of the list, +1 would be easy protest bait.

Oh yeah, STi is A stock, not B.

[BDL Motorsports]

I have downloaded the 2008 rules but have not gone through them yet. I had a head gasket go in 2005 ( my Mustang ) and have not run autocross in about 2 years now... odd winter event.

I am only testing the car and not doing a series... so if i am in A or B SP ... not an issue with me.

I am +1 with my street rubber... will be on 17's for events.

We are using SCCA rules ( in Western Canada ) and I thought I seen some STI's in B stock before....


I will go through the rules more once I know the STI will be my dedicated solo II car.

Thanks all.