I searched but didn't find any specific discussion of why the factory recommended tire pressure at 36F/44R are so high. When I first the numbers on the door jamb, I had to take a second look and make sure I didn't read it wrong. I remember the GT3 I had was at something like 32/39. I have a Viper w/ probably same weight as the 997TT running 28/32. Are most of you guys running this high of pressure?

 

Yes, it is. For "partial load" (driver only) the cold pressure (car un-driven, no direct sunlight on tires) recommendation is 33/39, at 20 C/68 F, and lower when the ambient temp is lower. My car for example reads 31/37 in the morning when ambient temp is in the 50's.
If you are not familiar with the very convenient TPMS system in the Turbo & how to use the stalk to check the differential pressure readings, you might want to click on that Bilstein thread in my signature below and go to the last page. Some of my somewhat coherent rambling on tire pressure -- street usage -- is there.
http://www.rennteam.com/forum/thread...html#p20079160

 

FYI the 993tt which had a lower weight than the 997tt even ran 36/44 tire pressures, but on 18"

 

I run it around 33/35 cold for around town driving.

With the bad roads here if I run the rear PSI anywhere near what its recommended the rear feels too harsh over bumps.

And yes, my tire pressure sensor is always lit It comforts me along with the red exclamation mark for no third brake light.

My dash is like a christmas tree.

 

eclou,

What tire pressure do you keep on your 997TT at the track? Just curious as I of course have no experience there.
How often do you have to check to bleed off? Is there a range you try to keep the pressure within?

When I was at the Porsche autocross event, I vaguely recall seeing 44/44 on the Cayman S. Seems to be awefully high. Is that typical of what people do at the track?

 

Get some Nitrogen in the tires and I run it around 32/35, Depends on how you drive...How agressive do you drive?

 

mine are 34/40 after being warmed up - all on nitrogen..

 

Actually per the manual....the 36/45 is for the "fully Loaded" driving and 33/39 is for the "partially loaded".....

 

Can, at the track on R compounds like MPSC I like to start at 28F/30R cold PSI, some guys go even lower on the GT2s. After a few laps they are hot and running around 40-44 PSI. On a street tire I generally shoot for 36/44 hot at the track. You'll find yourself constantly bleeding down the tires through the day. Hoosiers are completely different. I'm also happy if my pyrometer reads 140-160 as evenly as possible on the tires, immediately off the track. Tells me I'm driving the car hard enough.
On the street I use the standard OEM pressures for DD.

 

When I run 44psi in the rear I have seen the center of the tire showing wear.. I run mine at 34/40 hot.

 

Sure. Fully loaded is higher, but if and only if you have 2 passengers PLUS luggage.

I think everyone is talking about partial loaded here -- up to 2 people in car. For that, the range is around 31/37 cold, and 33/39 warm, for street.

Doug, thanks for the interesting info on track tire pressure.

 

Read the various information links on the Tire Rack web site - pretty good generic education for many of us.

 

Yup, Tire Rack has some great info!

 

At the beginnig it was running 35-40 cold / 38-45 hot.

Then i made a trackday and dropped a bit the pressures to 32-38 cold. Even so, it went to 46-50 on track but only 36-42 on the road.

Now i'm running 30-36 cold / 34-39 hot. I have a trackday in 2 weeks in the same track, but this time the air temp will be around 45ºF higher. I have no clue what pressures to use. Can someone help?

It has michelin PS2.

 

I also noticed the TPMs reads quite low compared to my gauges. I double checked the reading using two different good quality gauges this morning and both read 33F/39R cold. Then when the reading come on, TPMS only showed 29F/35R, off by 4 PSI both F and R. Do your TPMS readings agree w/ your tire gauges?