I am experiencing some tire pressure management problems on my 2008 997.1 with 2,000 miles. Set pressures cold, 37 front / 44 rear. After driving tire pressures rise as they heat up, which is expected. Although, manual indicates the TPC compensates for the rise due to heat. After a 2 hours driving, I returned to the car (after two hours) to find one front -3 lbs and a information alert (!). But my tire gauge indicates equal pressure with the opposing tire. I had to reset the TPC. Any suggetions on TPC and who makes a calibrated pressure gauge?

 

To start with I believe that you have way tooo much pressure in your tires. Unless you're heavily loaded I believe that you shouldn't be higher than 34/40psi.

TPC can be erratic and I look for it to indicate extreme sudden changes such as a blow out. A high qulaity tire gauge gives the most reliable reading.

 

wow, go 33 fronts / 39 rears, the pressure setup you have is for a FULLY loaded car and is way too high for just a driver + passenger. it may lead to more road hazard (e.g., bent rims, bubbles, etc)

 

Speaking of TPS. Is this an option or standard feature? It is another item that does not show up for me on either the dash or PCM.

 

+1 on your pressure being much too high. As for the TPMS, mine acted up similar to yours when my car was new and may have been a result of excessive cold tire pressures. Of late it seems to be dead on most of the time with cold pressure set at 33 and 39. Either way, I rely on the cold pressures I set with my tire gauge. TPMS is their to tell alert you when you've got a flat.

 

standard on 2007 and on vehicles

 

I am reading this as "standard on 2007 and option on other vehicles"? So, would have been an option for 2006 and if it's not listed on the window sticker I don't have it. No big deal as I check my pressures every Sunday before the work week. it's just funny that it's standard on a Scion XD and not a $100k sportscar. But I am learning that Porsche loves to offer options. LOL.

 

I've been told Porsche dealers charge for air.

 

Another vote for tire pressure being way too high. Look in the manual and you will find different pressures for different loads.
The pressure you are useing 37/44 is for 4 passanger and full load of luggage.

 

It became federal law for passenger cars starting in 2007. Some manufacturers started putting it in earlier. For example, my 2006 Acura has it, but my 2006 997S does not.

Honestly, since my 997S is not my daily driver I don't mind not having it. I can just check the tires myself... I don't need any additional Porsche electronics...

 

This is the tyre presure for 4 passengers with luggage (if you ever can fit some). That said it doesn't explain unstable measures and though it is the maximum recommended by Porsche, you are still within their boundaries. Slightly over-inflating is less comfortable, slightly bumpier and get you uneven wear by the centre of the tyre. But 911s often wear out tyres at the outter shoulders, so while this is a problem it is not a major one.
Simply I think there is something wrong with the sensor inside your wheel that transmit data to the TPM system.

 

Would the appropriate pressure (33/39) be the same for non-OEM tires (i.e. Nitto Invos)?

Also, I thought higher pressure offer more protection against road hazards and not less. Am I mistaken

Thanks

 

On the track I run the Nitto NT01 a little lower which keeps them from getting that greasy feeling once fully warmed up. For Invos on the street I would go 33/39 unless it exceeds or is very close to the mfgrs max inflation (on the tire) - and it might be worthwhile to check the Nitto website to see if there are any recommendations there.

I also think more pressure gives better protection of the rims against pot hole, RR tracks and similar damage, but I don't have any source or data for that belief. I've been running my street tires at 37/44 regardless of load and the wear is even (if anything still light in the middle) and tire life very good. The ride is firm but I do like that! Maybe on the next set of tires I will try lower pressures.

I run my winter tires (on 18 in rims) at lower pressures (closer to 32/38).