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Traffic Surgeon
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Discussion Starter · #1 ·
Been doing some research and I am trying to determine the best tire pressure to run at the track this weekend. I have the staggered 17's on my car. I've read a few posts that recommend not going over 40psi, so I'm not sure how much more, if at all, I want to change my daily 35f/38r setup. Maybe 38f/40r...? :dunno:

TIA
 

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Car Junkie
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I'm curious about this too, for both track and autocross. On the track, your tires are likely to heat up significantly, which is probably why you might not want to exceed 40 psi cold. Anyone out there with track experience?
 

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I like cookies.
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Chris330ci said:


Even with the staggered setup? BTW AFAIK, I won't have access to air... :(
You may want to run higher pressures in the front with staggered tires, that's why I suggest equal pressure and adjust.

Buy an air compressor, they are cheap.
 
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With the staggered setup, I start 40F 38R and usually end up around 41-42F 36-38R. You need to have MORE up front that inteh rear to offset the understeer inherent in the stagger. THis is why any serious track junkie who buys new rims ditches the staggered setup for 235s all around.
 

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OMGWTFBBQ
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TD said:
You need to have MORE up front that inteh rear to offset the understeer inherent in the stagger.
From an autocross perspective (which grew by leaps and bounds yesterday at the SCCA event at FedEx Field yesterday...great course which taught me more than I would have thought)...

By adjusting tire pressures, you adjust how much traction that a tire can give you. By running the rears lower than the front (up to a point) you are reducing the amount of traction at the rear to match what's available at the front, which will change the car's balance. The car may feel better, but that won't make it go faster directly. For some people, having a neutrally balanced car is so much easier to drive that they can turn in faster times despite having less actual grip available.

I like Nate's 40/40 starting point. Learning the lines and gaining experience is going to be the biggest factor initially, and it won't really matter too much what pressures that you're running. Once you start getting consistant is when you should start making adjustments.
 

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I don't know if this applies for the track, but for autocross a good rule of thumb is to add 10 PSI to your street pressures (measured cold) as a starting point. Then you can chalk or shoe polish 3 or 4 points where the sidewall meets the tread and adjust pressures based on how much rollover you are getting on the sidewall.

Remember that up to a point adding pressure to a tire increases traction. If you are pushing, add pressure to the fronts (or decrease the rears). If you're loose, add pressure to the rears (or decrease the fronts).

Of course all bets are off if you're using R compound tires since the sidewalls are too firm to rollover and different pressure rules can apply. Then you need a pyrometer to measure the temp of the tires and adjust based on that.
 
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