Thanks for the feedback Eldertec.

 

Okay so I went and got nitrogen put in my tires. I got them filled to 33 front and 39 rears. When I pulled out of the shop the tps read exactly that. Now because where I live its still cold in the morning ..... -1 degree celcius or lower the tires read as low as 29 front and 36 rears. Should I be doing anything about this?

 

The 997.1 TPMS is not as accurate as the 997.2 system. Just get a good quality tire pressure gage and keep it in your frunk to monitor what the delta is when tires are cold. A must have for those who track but practical to have anyway

 

I do know there is a formula of how pressure goes down as the ambient temperature falls but I forget what it is. Recheck what your TPMS says as outside temps get warmer but the car is still cold.

 

If the dashboard indicates low tire pressure and the weather is cold, it's better to ride for a while... More than likely the tire pressure is correct. If the sensors are bad, then just get them changed. Dealers are expensive so a better choice is getting them online. The ones on Ebay or Amazon will work just fine. Else TitanTpms.com cover a large range tire sensors for Porsche. Just be aware of the Radio Frequency.

 

That advice is contrary to anything I've ever been told.

 

I agree. If my sensors says my tires are low then I check regardless of the weather. Cold is when you check. If pressure is ok then the TPMS maybe bad.

 

Agree with jhbrennan and RaidersR1 on this. The warning indicator generally won't indicate low unless the pressure is really low. I would add air if the dash light comes on.

In 997.2 models (not sure about 997.1), the TPMS system actually monitors both the tire pressure and the tire temperature. While the absolute pressure display shows the real pressure of the tire, the delta pressure display (+/- some number) takes the tire temperature, tire pressure, and the tire loading setting that has been entered into account in its report. If you want to observe/adjust pressures based upon your load settings (it also considers summer/winter and 18"/19" tire diameter) regardless of the tire temperature then you can use this display.

 

One other thought on your suggestion of eBay or Amazon. This forum is loaded with horror stories about many of the non-OEM TPMS sensors being very problematic. Look them up. I went with OEM sensors from one of the Porsche dealers online that discounts them. I thought it was money well-spent not to worry if I was getting compatible ones with good batteries or not... although I have heard a handful of success stories with others well. Mine showed up from with a manufacture date of only two months earlier and worked with nary a problem.

 

I have mine set at 33/39 (997.2 Turbo) and my TPMS reports -5 under inflated. Comments....can you change the recommended via PCM?