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What tire pressure with 305's in rear.

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Old 07-30-2008 | 05:58 PM
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What tire pressure with 305's in rear.

I have searched and could not find my answer. What is a good street and track tire pressure to run with 305's in the rear? Should it be the same as the 295's? I have them at 40 psi currently.
 
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Old 07-30-2008 | 06:05 PM
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tire pressure should be what the manufacture of the car recommends, the wider tire doesnt really change that. I would start out 5lbs less than that for the track then adjust your pressures accordingly so that you have proper wear on the shoulders of the tires when at speed thru corners amd the tires are up to temp. You want to use the entire shoulder of the tire, anything showing wear to high on the shoulder is over inflated and if your are going past the shoulder tread and onto the sidewall it's under inflated. Your pressures will change constantly thru the day depending on temp, driving style, etc.
 
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Old 07-30-2008 | 06:28 PM
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Thanks b911s. I figured it would be the same. I usually go by the door sticker, but was told those pressures are for max load of the vehicle (I rarely have even a second person in the car). I run 40 psi in the rear. Hopefully I will see the correct wear pattern.
 
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Old 07-31-2008 | 04:20 AM
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When cold [street]...

37 psi - front

44 psi - rear

*According to the sticker on the doorjamb*
 

Last edited by MelsM3; 07-31-2008 at 11:49 PM.
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Old 07-31-2008 | 11:25 AM
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Originally Posted by mdrums
Just follow the owners manual and use 33 front and 39 rear. You get better handling with these pressures on the street. The higher the pressure the more the car can and will slide.

For the track on PS2's depends on the track and how fast your are driving. If you are starting out at a DE don't worry about presures and go with the 33/39. After you start to learn the track and are picking up speed come in from a hot lap and check pressures and keep the front and rear at 38 or so but no more than 40. Actually at the end of my PS2's life I was in solo group and found that 35 hot worked best. My tire pressures at Sebring were increasing by 10psi from cold to hot.

Thanks for the info mdrums!
 
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Old 07-31-2008 | 06:48 PM
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Originally Posted by MelsM3
When cold [street]...

37 psi - front

44 psi - rear
Thats WAY to high. 33/39 cold
 
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Old 07-31-2008 | 06:59 PM
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I'm with mdrums re: PS2 pressure on the track. Whenever my rear tires got more than 40 hot, the car got real squirrelly. (My car's sticker states 37 and 44 cold.)
 
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Old 07-31-2008 | 07:50 PM
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Just wondering, why are rear tires higher than the fronts?

Originally Posted by lardog
Thats WAY to high. 33/39 cold
 
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Old 07-31-2008 | 09:09 PM
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Originally Posted by honeybadger
Just wondering, why are rear tires higher than the fronts?
Weight and lateral force during turns I suspect.
 
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Old 07-31-2008 | 10:54 PM
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Originally Posted by MelsM3
When cold [street]...

37 psi - front

44 psi - rear
Man those are hard tires!

Isn't that a bit much?

I don't know Porsche pressures but even Ferrari does not go beyond 39 lbs!
 
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Old 07-31-2008 | 11:54 PM
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Originally Posted by honeybadger
Just wondering, why are rear tires higher than the fronts?
The front/rear weight distribution, is approximately 40% / 60%.
 
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Old 08-01-2008 | 08:16 AM
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Guys, READ THE OWNERS MANUAL!!!!!....those 37/44 pressures are ONLY for 4 adults with the front full of luggage. More weight in the car on a trip Porsche says to put more air in the tires.

If you use the 37/44 pressures for any type of spirited driving you will end up with too much heat and thus pressure in the tire. Look on the tire sidewall and there is a max pressure stated.

IF all you ever have in you Porsche is you and your girl and some luggage stay at the 33/39 PSI cold which is done at 68 degree F. Any change in ambient temp + or - of 68 by ten degrees you can adjust around 1 psi + or -. Again all this is covered in the OWNERS MANUAL.
 
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Old 08-16-2008 | 06:38 PM
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I routinely run 33 and 39. It's always higher in the rear because all the weight is back there. That's with no real loads.
 
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Old 08-16-2008 | 06:57 PM
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Originally Posted by Edgy01
I routinely run 33 and 39. It's always higher in the rear because all the weight is back there. That's with no real loads.
Not even close for Ferrari. It's usually 29-30 front and 32-33 rears.

Why is Porsche so much more?

I have seen an 08 TT cabrio showing 40 rear.
 
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Old 08-16-2008 | 10:18 PM
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Originally Posted by mdrums
Guys, READ THE OWNERS MANUAL!!!!!....those 37/44 pressures are ONLY for 4 adults with the front full of luggage. More weight in the car on a trip Porsche says to put more air in the tires.

If you use the 37/44 pressures for any type of spirited driving you will end up with too much heat and thus pressure in the tire. Look on the tire sidewall and there is a max pressure stated.

IF all you ever have in you Porsche is you and your girl and some luggage stay at the 33/39 PSI cold which is done at 68 degree F. Any change in ambient temp + or - of 68 by ten degrees you can adjust around 1 psi + or -. Again all this is covered in the OWNERS MANUAL.
Good advice. The door jamb label has a note that says the (higher) pressures shown on the label are for a fully loaded car, and that the pressures shown in manual should be used if weight of driver and passenger etc is less than 352 pounds.
 


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