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991.2 track tire pressures

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Old 07-17-2017, 03:56 PM
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Bob T
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Default 991.2 track tire pressures

Does anyone have some tried and proven ultimate hot race track tire pressure settings for 991.2 running 20" Pirelli P Zeros? I have been running my 2017 cab on Area 27 and have experienced pressure increase up to 15 psi, to over 50, which surprises me.
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Old 07-22-2017, 07:57 PM
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mdrums
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Depends on the track, driver and alignment settings.

Rule of thumb is with a advanced driver a tire will heat up around 8-10 psi. Seems most tires run best hot from around 30-34 front and 32-36 rear...again depends on the tire, driver, track and alignment settings.
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Old 07-22-2017, 09:39 PM
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Bob T
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Thanks for that mdrums. To clarify please: do you mean the pressures you quoted are the STARTING pressures when cold, or the ultimate pressures after they have risen 8-10 psi?
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Old 07-23-2017, 08:18 PM
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Ultimate hot pressure. Starting pressure will depend on outside air temperature and hot fast hard you drive and heat tires up.
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Old 02-11-2018, 12:04 PM
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Same question. The door sticker calls out 37/44psi for the P-Zeros, max inflation is 50psi. Assuming advanced driver on a day with moderate ambient temperature (say 75 degrees), factory alignment, and on a short track (Laguna), what pressure would you start from? I don’t have a pyrometer and on my next track day the thing I want to focus on is tire pressure.
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Old 02-16-2018, 01:56 PM
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Mr. Turtles
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Originally Posted by jnolan View Post
Same question. The door sticker calls out 37/44psi for the P-Zeros, max inflation is 50psi. Assuming advanced driver on a day with moderate ambient temperature (say 75 degrees), factory alignment, and on a short track (Laguna), what pressure would you start from? I don’t have a pyrometer and on my next track day the thing I want to focus on is tire pressure.
Start with around 28psi/...you can't go to low otherwise they could damage. If you go lower on first session you'll need to do a few slower laps until they are warm. The first session you can live with the high tire pressures that will most likely result (close to 40psi) or just stop after 5 or so laps and adjust. Either way adjust them right after your first session when still hot to around 32-34 PSI and you should be good the next few sessions. Always check and correct PSI after each session though. I always start my MPSC2's at 26PSI but I had TPMS on to let me know when they were warm.
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Old 02-16-2018, 04:32 PM
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Thanks! That helps. I’m at Laguna on Sunday and will start with 26psi and go up from there.
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Old 02-23-2018, 10:32 PM
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@Turtles, I followed you advice with good results. Thanks again.
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Old 02-23-2018, 11:51 PM
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Glad it helped, keep adjusting to what works best for you. Everyone drives a little different, has a different set up, car, etc, so what works best for you might be a slightly different.

Mark
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