What is Street tire index for?

[Mnbodyman]

I just signed up for my first autocross event on the 21st of August. I'm registered under D-Stock for my 2002 Subaru WRX Wagon. I looked on the SCCA website and this seemed to be the right category for my condsidering my car is stock. My question is: Should I have entered the Street tire category since I will be running my all season tires? I've noticed that other people from the stock category are in there also. Should i be? Thanks for the help.

[StevenMosley]

I would personally run in DS, but since this is your first time out you can run in the beginner class called "SI".

The street tire index class takes your raw times and bases them on the PAX system which is kind of like using a handicap for golf. It basically a system for scoring car setup/driver across classes.

[pinhead]

you can run either class. Since it is your first time, you might want to think about running "SI", which is sort of a beginner class, as well.

The Street Tire Index class uses a set of equalization factors (called pax) to find the winner. This allows the slower cars to compete "fairly" with the faster cars. Basically, you take your raw time and multiply it by a scaling factor. The faster the class your car is in, the higher the scaling factor is. So an H-Stock Mini Cooper will receive more of an adjustment to it's time than an ASP Z06 will. SO in principal, the guy in the Mini Cooper could run the course several seconds slower than the ASP Vette, yet still beat the Vette 'on the index' as they say.

edit - Steven drives AND types fast than me ;)

[MNbiker]

Either sign up for DS or SI. First time out, you'll get beat by Fitz & Nikki in DS, but that is the correct class for your car. In SI, you'll have a chance to compete against other novices. You can only win SI once, then you have to move into a "regular" class.

Seeing as it's your first event, I'd highly recommend having an instructor ride with you for your first run or two. I'm one of the co-chairs for the 21st event, and will be available for ride-alongs. As luck would have it, I also happen to drive a WRX wagon - albeit one that's no where near stock at this point.

-Steve Garnjobst

[Mnbodyman]

Thank you very much for the great advice everybody. I will most likely be switching to SI so I can not get completely demolished by the competition.

MNBiker - It's kind of a wierd coincedence that you have a 02 WRX wagon just like me and we also live in the exact same area. I live in North Saint Paul which is right by Maplewood. Well I hope to see you at the event, I'm all registered and really excited for the day to come.

Thanks again everybody.

[fitz]

For the record, I ran the entire season except MOWOG 7 on Street Tires (OE no less, not even something fun) but opted to run in DS instead of DSt for most of the season. So it is possible to at least by competitive on street tires, depeding on the class of course.

[DCM]

OK Fitz, we're gonna' have an argument.

The street tires of today, this day and age, just ain't anywhere close to what street tires were a mere 10-12 years ago.

Back in my 'yout' street tires were lucky to get 30,000 miles on them. they were bias tread, with some 'wide ovals' that had tread about 5" wide on 4.5" wheels. Todays cars with standard 7" wide rims with 40-50- 60- widths are twice as wide, and way better grip. Plus the cars suspension of today is more like Ferrari's of the 60's.
DCM:flame:

[ps13drifter]

lol, i sure don't get 30K out of my street tires:D