Here's the situation

I've been autocrossing once a month since June of this last summer (2 times with my 04 WRX) and the rest with my s2000.

I've been racing my 02 S2000 for 2 months now, I have replaced my tires with Porsche spec fronts S02's and S2000 S02's rear. (got a great deal on the fronts) Now the questions.....

Air pressure: I've heard many things about it, but is it the lower the pressure the greater grip to an extant, or is it higher? Could I play aroud with tire pressures in the front and rear to play around with trying to eliminate some understear or induce more oversteer?

Also I just got an alignment this last week, found out I was racing with an alignment that was way off, which to me made my car seem real loose. My question is, I usually take out my spare tire and jack and stuff, but would it be beneficial to keep that extra weight back there to put some more weight over the rear tires? Or is there really no difference.

Please be patient with me, I think i have a pretty good car knowledge but I'm just trying to get the best times I can get and learn more about setting up my car with limited resources, any help would be greatly appreciated.

 

First, the Porch (intentional) tires are not the same size as the OEM S02s. Just so you know.

36f/32-34r is a decent starting point for street tires since they don't have the sidewall stiffness that an R-compound tire does. Use pressure to fine-tune your handling.

Understeer on an S is generally induced by bad driver input (e.g. braking too late and having to yank the wheel or overdriving a turn with too much power rather than letting the tires do their job). Experience and a school would help a lot.

The alignment is a big, cheap item. Keep an eye on it.

The weight from the spare is really negligible although you have to use some energy to accelerate/decelerate/turn the thing. It's not enough to worry about until you can run with the big dogs. The tools must ALWAYS come out since they're not tied down.

BTW, did you read the FAQ at the top of this forum?

 

The forst couple of times I autocrossed in my S w/ street tires, I couldn't believe how bad the handling was. Here's what happened:
The SCCA recommends setting street tires abotu 10psi higher than you would use on the street. When I did that, I was understeering on the entry of corners and fishtailing on the exits. I thought "where is the handling that they said this car had?"

Then I talked to another S owner who was there and he said he set the pressures at 32 all around. So I tried it and it was much better w/ predictable and controlable(sp?) handling.

So I'd try going with at least equal pressures all around. Of course a few autocrosses later, I bought race tires and handling was even better.

Warren

 

check pedalfasters faq on top of this thread. It is a bible for auto xing the S. Since the S usually oversteers on stock tires and reccomended sized r compounds most of us run 2lbs more presure on fronts at all times to help balance car. Some use a 4lb differance between front and rear. We start as high as 42f and 40r and drop down to get it right between runs . Lowest I've run is 32f 30r.

 

With S02s, I use 35-36F and 32-33R. They S02s actually have a very stiff sidewall for a street tire, at least as stiff as the RA-1s I currently use so I use the same pressures both RA-1s and S02s. To correctly get tire pressure, you want to chalk your sidewalls and keep lowering pressure untill you have rolloverm, than raise psi a little bit. I rolled over my fronts with less than 35 psi, I have not had the problem on the rears with 33 psi.

 

My advice is to set the pressures at anything you want that's reasonable. Then don't mess with them. Forget about it. Just focus on driving... there is soooo much to think about and to pay attention to regarding your lines and techniques. Use this time that you're not competitive to focus on the driver alone and don't distract yourself with street tire pressures.

... and have fun.

 

Thanks alot for the info and answering some of my questions, My first two weekends with my s2k I had quite a bit of understeer sometimes, but that could of also been to my alignment that was off by alot, second I was running very competitive times with all season tires, 6th place overall in my city, all the other cars infront of me were running slicks and competition tires. I'm excited about my new set of tires and my alignment and I was just seeing about getting a better edge on things. And about not getting the s2000 fronts, I got the ones I got for $70 plus shipping for barely worn tires, great deal off of ebay couldn't pass it up. Thanks again for all the help!