what tire pressure are you guys running "on and off the track?"
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With PS2's you want to keep the front and rear around 38 psi...no more than 40 in the rear or you will loose grip. I always liked around 37 front and 38 rear. These are HOT pressures. I started out at around 29-31 cold depending on the weather and how hard I was driving at the time.
When I moved to R-Comps with the Toyou RA1's and then the Toyo R888's I always liked the grip when these tires where at 36 front 37 rear.
When I moved to R-Comps with the Toyou RA1's and then the Toyo R888's I always liked the grip when these tires where at 36 front 37 rear.
IMO, at regular tracks, the quick rotating rears would sometimes feel a little unstable at higher speeds especially for our rear weight biased pcars. The lower front pressure is inline with the inherent neutral/understeer Porsche have engineered into our cars. It will also reduce the undesirable front bounce that is dreaded in track use.
For street, 36/41 would allow better heat cycles on your calm daily commutes.
But for track use, drop at least 4~5 psi to start should be fine. Of course, this is without any suspension mods and is dependant on track condition, driving skill/style, weather, blah blah blah...
An old and quick trick for correct tire pressure is to chalk your tire grooves/walls during track days. After a few laps, come in and see how much of the chalk have rubbed off the walls to check. If you are wearing considerably into the walls, then either you are scrubbing the tires or you are under pressured.
Just my .02
Last edited by muifast; Feb 16, 2009 at 08:42 PM.
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Actually the tracks I run at are regular tracks infact internationally famous. I run at Sebring for example. Very fast track with long straights smooth and bumpy sections tight corners and sweepers.
With typically how Pro/Solo courses are set-up, meaning short straights, slalom, or tight radius turns, I would imagine these type of pressures would induce a better turn-in and quicker rotation for the rears to cope with the Solo tracks.
IMO, at regular tracks, the quick rotating rears would sometimes feel a little unstable at higher speeds especially for our rear weight biased pcars.
For street, 36/41 would allow better heat cycles on your calm daily commutes.
But for track use, drop at least 4~5 psi to start should be fine. Of course, this is without any suspension mods and is dependant on track condition, driving skill/style, weather, blah blah blah...
An old and quick trick for correct tire pressure is to chalk your tire grooves/walls during track days. After a few laps, come in and see how much of the chalk have rubbed off the walls to check. If you are wearing considerably into the walls, then either you are scrubbing the tires or you are under pressured.
Just my .02
IMO, at regular tracks, the quick rotating rears would sometimes feel a little unstable at higher speeds especially for our rear weight biased pcars.
For street, 36/41 would allow better heat cycles on your calm daily commutes.
But for track use, drop at least 4~5 psi to start should be fine. Of course, this is without any suspension mods and is dependant on track condition, driving skill/style, weather, blah blah blah...
An old and quick trick for correct tire pressure is to chalk your tire grooves/walls during track days. After a few laps, come in and see how much of the chalk have rubbed off the walls to check. If you are wearing considerably into the walls, then either you are scrubbing the tires or you are under pressured.
Just my .02
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IMO, at regular tracks, the quick rotating rears would sometimes feel a little unstable at higher speeds especially for our rear weight biased pcars. The lower front pressure is inline with the inherent neutral/understeer Porsche have engineered into our cars. It will also reduce the undesirable front bounce that is dreaded in track use.
But for track use, drop at least 4~5 psi to start should be fine.
Thanks
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This is a setting that is similar to the balance you are used to on the street, then as you go through the day, try to find a balance that works for the track and your driving style/skill by altering f/r pressures.
If you will notice, you are starting out with a little understeer, then as the day goes on, you are trying to reach a more neutral balance.
Just my observations. Have fun...
Last edited by muifast; Feb 16, 2009 at 11:28 PM.
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Now thats a complex question. The 2009 997 manual gives 3 different inflation pressure instructions drawing on various sources. 1) Door jam sticker (Which does not differentiate by tire type or size or load) 2) Computer based TPMS and Temp correction (differential) adjustments in a +/i PSI reading the car wheels are off of the desired pressure. 3) The table at the back of the owners manual (also makes no adjustment of wheel size and tire type). All 3 sources can give you different pressures.
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What car and what tires? Weather conditions? It all depends.
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Now thats a complex question. The 2009 997 manual gives 3 different inflation pressure instructions drawing on various sources. 1) Door jam sticker (Which does not differentiate by tire type or size or load) 2) Computer based TPMS and Temp correction (differential) adjustments in a +/i PSI reading the car wheels are off of the desired pressure. 3) The table at the back of the owners manual (also makes no adjustment of wheel size and tire type). All 3 sources can give you different pressures.
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When putting the question about what to do in light of the three varying sources of pressure for the car, my salesman provided me with this advice:
You are the 3rd customer in the last 2 days that has some sort of Tire pressure question. The best answer I have been giving out is that as long as you are in that range of 35-38psi in the front and 40-43psi in the rear it really is a personal preference.
Which explains why my car was delivered with such a high back pressure, compared to what the various sources from the manual are telling me.
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Actually the manual tells you that under a normal load...2 passanger and 1 suitcase up front that for the 2005-08 cars run 33/39 psi based off 68 degrees F. The 2009 manual tells you under normal load to run 34/39psi based off a normal load of 2 passangers and 1 suitcase at 68 degrees F.
The higher PSI are for 4 passangers and more luggage up front. How many of us drive around with that type of load? Not many I will guess.
Your car was delivered to you with higher PSI because Porsche and/or the receiving department at your dealer pumped them up to prevent flat spots.
Look in the manual and you will see the explaination for tire pressures.
The higher PSI are for 4 passangers and more luggage up front. How many of us drive around with that type of load? Not many I will guess.
Your car was delivered to you with higher PSI because Porsche and/or the receiving department at your dealer pumped them up to prevent flat spots.
Look in the manual and you will see the explaination for tire pressures.
When putting the question about what to do in light of the three varying sources of pressure for the car, my salesman provided me with this advice:
You are the 3rd customer in the last 2 days that has some sort of Tire pressure question. The best answer I have been giving out is that as long as you are in that range of 35-38psi in the front and 40-43psi in the rear it really is a personal preference.
Which explains why my car was delivered with such a high back pressure, compared to what the various sources from the manual are telling me.
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off track in 25F, I've been very happy running 30front, 33rear...cold, once they warm up they reach 32front and 36-37rear. I find that this also helps keep the tires from getting warn down as quickly.
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BTW, my car (purchased used) did not come with TPMS so I purchased a Hawkshead Racing Pressure Track wireless monitor (http://tinyurl.com/dxwplh) from site sponsor VividRacing. I've not rebalanced the tires because I haven't tracked the cars (and haven't noticed any obvious vibration at 'normal' speeds) but it is fascinating to be able to 'watch' realtime temperature status, changes as you drive, etc. For those on this thread who are interested in nailing this down, it is a useful gadget.
And to be clear (fair harbor statement goes here) I have no business or other relationship with the folks at VR. BTW, VR's comes in red. I've seen another equivalent in black. I painted mine
And to be clear (fair harbor statement goes here) I have no business or other relationship with the folks at VR. BTW, VR's comes in red. I've seen another equivalent in black. I painted mine
Last edited by Verde; Feb 19, 2009 at 10:18 AM.