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Ha sanyone run an autocross with the OEM Potnzas? I'm concered about debeading those soft, low sidewalls?
 

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Discussion Starter · #3 ·
Thanks madhatter. First autox of the year for SCCA New England on 3/30 and will be running my new ST for first time on the Potenzas if there's no snow and it warms up a little. Otherwise I'll put on 15" snow/ice tires.
 

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I have done two events as well in mine, hopefully a third this weekend. The potenzas aren't bad, though not near as good as the dunlop zII's (another FiST had them and he smoked me..). I pumped the front up to 42 psi and the rear around 50.
 

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Thats really high pressure, when those tires warm up youll be over 60psi, ya its a one lap race but i would stick closer to stock psi.
That's why you bleed them down before each subsequent run. And they never really warm up. At least, not in 60degree temps. In August, when tarmac temps hit 140 it might be a different story.
I've done some testing. Those are what pressures i've found the OEM tire likes to be at for the car to handle well.
 

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That's why you bleed them down before each subsequent run. And they never really warm up. At least, not in 60degree temps. In August, when tarmac temps hit 140 it might be a different story.
I've done some testing. Those are what pressures i've found the OEM tire likes to be at for the car to handle well.
Oh, you mean you actually tested? Pfft, I'd believe the Internet before I'd believe real world testing! :p
 

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I check after each run, and the rears never really gain more than 1-2 psi. Not a whole lot of heat generated back there since one or the other is usually up in the air. As for the front, 42 seemed right for the surface I was on to keep from rolling into the sidewalls...


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Has anybody actually taken inside/middle/outside tire temps with their pressure settings? I'd be more interested in getting the best contact patch, I can make the car handle how I want it to with technique.
 

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Say u start at 40 cold, u exit track at 45 hot. U bleed down to 40, tires cool now ur at 35. Now ur low on pressure, on track again and tires get hot u exit track and ur at 43 or so u bleed down again to 40 but ur really in low 30's cold. Do that a few times now ur starting cold in the 20's, ull be back in the 40's after a hot lap but ur in trouble cause tires and air is super hot, remember all the firestone ford blow outs in the 90's. All low tire pressure issues causings tires to over heat at speed. Id pick a presure and leave it for the day.
 

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Say u start at 40 cold, u exit track at 45 hot. U bleed down to 40, tires cool now ur at 35. Now ur low on pressure, on track again and tires get hot u exit track and ur at 43 or so u bleed down again to 40 but ur really in low 30's cold. Do that a few times now ur starting cold in the 20's, ull be back in the 40's after a hot lap but ur in trouble cause tires and air is super hot, remember all the firestone ford blow outs in the 90's. All low tire pressure issues causings tires to over heat at speed. Id pick a presure and leave it for the day.
Start at 40, run and come off course, pressures will be about 45-46. While you wait, pressures will fall by a psi or so. Wait until a few minutes before you line up for your next run, and bleed back to 40. Rinse and repeat. Pressures will fall back down when the tires are cool again, but that won't happen during a normal run group.

I couldn't imagine running an event without bleeding excess pressure.
 

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Has anybody actually taken inside/middle/outside tire temps with their pressure settings? I'd be more interested in getting the best contact patch, I can make the car handle how I want it to with technique.
Camber is going to be the only thing that will even it out from what I've seen so far, and in GS, it's kinda limited as to what you can do. Tire pressure is going to help with roll-over on the shoulder, but a good alignment and crash bolts (a kit i'm still trying to verify is GS legal for this car) are really going to be the only thing that will optimize the contact patch.

The car turns in fine though, and i've not seen the tire killing tendencies that the Mini produces, so we've got a better camber curve at a minimum.
 
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