New to Autocross - Tire Wear

[NoVA_STi]

Hi,

I'm new to autocross and will be attending tomorrow's scheduled session in Bowie.

I've a quick question about tire wear. I'm driving a 2011 STi with the stock Dunlop SP600s. I'm told that it is a crappy tire, but it does well for what I currently do with the car (daily driving, pretty much). My question is, how much wear should I expect for a one-day autocross session? That brand and model is considered ultra-performance (summer) and they are sticky. I know such tires give good grip and feel but don't tend to hold up to extreme abuse (when compared to lower-tier hoops). They've close to 8K in mileage on them, all highway miles, so they are in good condition. Should I expect cupping or extreme wear, or am I worrying to much? I can afford new tires, but would rather plan for them now, if need be, than be surprised after a few autocross sessions.

Also, what of tire pressure for tomorrow's event? Stock pressure should be fine, I'm thinking, but wanted to ask anyways.

I'm still reading through the FAQ and forums, trying to suck it all in, so forgive me if I've asked of something that's common knowledge to you guys...I'm almost overwhelmed with information.

--
Ron

[v10climber]

When I bought my 08 STI with the SP600s I put at least 4-5 events on them and didn't notice any abnormal wear. I still got about 18k miles out of them. I'm on Star Specs now and I highly recommend them. I wouldn't anticipate any extreme wear on the tires. Especially from one auto-x event. Eventually you'll wear out the outside edge faster than the inside edge on a stock suspension car. If you are considering participating in many auto-x events you might consider camber bolts. They are cheap (<$50) and I got -2 degrees of camber in the front of my STI. If nothing else they help with preventing wearing out the outside edges of the tires after a considerable amount of autocrossing.

Stock pressures probably won't be enough to keep the front tires from rolling. I run 41 front and 39 rear and am happy with those pressures. If you have any questions tomorrow I'll be driving the wife's Red JCW mini and would be happy to answer them. There are a lot of experienced Subaru guys at the events if you have any questions.

[NoVA_STi]

Thanks for the insight!

I've another question. I'm trying to determine the Vehicle Index (for the bar codes). Are Dunlop SP600s considered street tires (I'm assuming so), or are they R-compound tires. I want to select the correct bar code. Dunlop's site doesn't have the wear rating for this tire. http://tire-ratings.findthebest.com/l/3557/Sp-Sport-600 has it rated as 200.

The below is what I get when I go through the bar code documents:

Tire Multiplier = 1.00 (street tires) [Stock tires - Dunlop SP600]
HP Multiplier = 1.03 (251 - 350 HP) [car is stock and rated at 305 HP]
Weight Multiplier = 0.99 (3,001 - 3,500 lbs) [car is approximately 3373 lb]
Vehicle Index = 1.0197

Seems about right, I guess.

[Nathan Atkins]

Yeah that looks right for a vehicle index, welcome to CDC it's my first season too, everyone here is pretty friendly and helpful.

Let me know if you decide to try different tires before those are totally worn and I'll buy them off of you, they're just the right size for my car!