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Old 05-12-2010, 08:47 PM   #1
RockoS13
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Default Autox Basic Newbie Tire Care questions-- Star Specs

I am autocrossing an STI, and have only done a few events in it. I was hoping someone could walk me through the tire maintenance that needs to be done to the car between runs. My car has two drivers, so it gets 8 runs in 1-2 hours, in hot weather.

Can someone please explain how useful the water spray is, say on a 90 degree day? The goal is to maintain constant tire pressure between runs, right? So if the water does not cool the tires down enough, air must be bleed to maintain the consistent pressure? How much does the water spray really help? Everyone does it but I don't see how it can really do much good.

I really am a newbie with the tires, and I want to be competitive, but I know I am not there yet. My tires are 245/40-17 Star Specs, BUT I am running them as my summer tires so they are probably hardened up a bit.

Thanks
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Old 05-12-2010, 09:17 PM   #2
Evil STI
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You'll need a sprayer, especially with a co-driver on a 90 day.

I hope your running decent front camber or you'll be shaving the hell out of the outside edges.

The importance of the above is multiplied by three if you are running them unshaved.

Dunlops like 36-38psi hot. Manage your rise and bleed down to your comfort zone. A pyrometer is the proper tool, but really only handy during a test and tune, not an actual event.

Of course, everything is course dependent and driver dependent.
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Old 05-12-2010, 10:30 PM   #3
dodwrx
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Tires have a temperature range in which they will produce the most grip. Warm tires are better than cold; however overly hot tires become "greasy" and grip will diminish. This is easy to feel with race tires, in fact Hoosier publishes temp ranges for their tires; but you should be able to feel the difference on the star specs as well.

On a 90 degree day with two drivers running heats your Star Specs will get so hot that it will burn your hand. When they get that hot use the sprayer to drop the temps. You still want them to be warm but not so hot you can't keep your hand on them.

In addition to spraying them you should use your tire gauge to manage the pressures. Between you and your co-driver you should be able to get this done between runs.

The other thing to watch for is outside shoulder wear. Especially the front tires on our camber challenged cars. A number of factors affect shoulder wear; camber, tire pressures, driving style. If shoulder wear creeps down the sidewall you should make adjustments.
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Old 05-13-2010, 03:50 PM   #4
jeisen
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I asked this same question in here like a week ago. I almost always have a co-driver (you know, because I'm such a nice guy) and run 225/45/17 Star Specs in ST. At the last event, there wasn't enough time between runs to switch all the numbers, etc. and check the tire pressures. I started at 36 cold and the fronts were over heating by the 4th group of runs. We were basically shaving the outside front treads down to shave depth from full depth (picture chunking out a pringle chip from the outside treads down the shave depth). This was with +4 deg caster and -2.75 deg camber up front.

I will now be starting at a lower pressure and bringing a water sprayer with me to events.

edit: here's the thread http://forums.nasioc.com/forums/show....php?t=1982085

Last edited by jeisen; 05-13-2010 at 03:51 PM. Reason: edit:
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Old 05-13-2010, 06:25 PM   #5
RockoS13
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Thanks for the useful advice, guys. I am going to get a water sprayer.

Jeisen, what did you use to adjust your front camber? Plates? I have a dilemma here because I need more negative front camber but I do not want to change the suspension at this time, and just putting in camber plates would lift the front of the car. Camber bolts do not sound like a reliable alternative.. but I need more camber up front.
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Old 05-14-2010, 08:19 AM   #6
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Quote:
Originally Posted by RockoS13 View Post
Thanks for the useful advice, guys. I am going to get a water sprayer.

Jeisen, what did you use to adjust your front camber? Plates? I have a dilemma here because I need more negative front camber but I do not want to change the suspension at this time, and just putting in camber plates would lift the front of the car. Camber bolts do not sound like a reliable alternative.. but I need more camber up front.
I'm running Ground Control coilovers and front camber plates.
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Old 05-15-2010, 02:33 AM   #7
makofoto
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Quote:
there wasn't enough time between runs
If you're running SCCA Solo events, you can demand (I believe) 5 minutes between race runs. If the grid is running too quickly ... pull off outside of the grid to service your car and then get back into grid.
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Old 05-17-2010, 03:47 PM   #8
BryanR
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Quote:
Originally Posted by makofoto View Post
If you're running SCCA Solo events, you can demand (I believe) 5 minutes between race runs. If the grid is running too quickly ... pull off outside of the grid to service your car and then get back into grid.
Yes 5 minutes minimum between runs, its in the rule book. If they're running too fast you can demand the time. It's usually not an issue at larger events, and if you're heats are small enough that you can't get 5 minutes between drivers, then the extra delay isn't really going to make for much longer of a day.
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