How accurate is the Porsche TPMS?

[gd]

Just checked the values on the TPMS display of my new 997tt against those on the label in the drivers door and they were wildly out... each tyre was showing about 5-8psi more than the recommended pressure.

But, is this accurate? The gauge on my air compressor was also showing a different reading, higher still, so I didnt know which to believe. For now I'm trusting the TPMS, not sure how wise this is tho.

Oh... and if not, can anyone recommend a good tyre pressure gauge?

Cheers
Gary

[hog 1]

I have always found the onboard TPMS to be accurate within .05 bar against an analogue pressure guage & that's across the 3 Porsche that I own.
Never go by the guages at air filling points at petrol stations. Adjust the pressure readings with a hand held guage from Halfrauds or similar to the sticker in the door, remembering to cross reference against tyre sizes and weight loadings on board.

[TPMS]

The pressure also depends on temperature change and /or altitude.
Temperature affects your pressure reading ON THE DASH.
Altitude affects pressure gauge reading.
On the placard, the suggest value is associates to 69 to 70 F (cold tire). Every 10 F affects about 1 psi.
There are gauges I know is altitude-independent. Temp compensation is very difficult to be done by gauge.
Hope it helps.

[mollytherocker]

TPMS said:

The pressure also depends on temperature change and /or altitude.
Temperature affects your pressure reading ON THE DASH.
Altitude affects pressure gauge reading.
On the placard, the suggest value is associates to 69 to 70 F (cold tire). Every 10 F affects about 1 psi.
There are gauges I know is altitude-independent. Temp compensation is very difficult to be done by gauge.
Hope it helps.

You created a new user just to answer this specific question? Why would you do that?

MTR

[Rrroro]

mollytherocker said:

TPMS said:

The pressure also depends on temperature change and /or altitude.
Temperature affects your pressure reading ON THE DASH.
Altitude affects pressure gauge reading.
On the placard, the suggest value is associates to 69 to 70 F (cold tire). Every 10 F affects about 1 psi.
There are gauges I know is altitude-independent. Temp compensation is very difficult to be done by gauge.
Hope it helps.

You created a new user just to answer this specific question? Why would you do that?

MTR

It's the TPMS Fairy, obviously.

[gd]

I knew that my new car is clever, but I didn't realise that parts of it would start posting information about itself on pistonheads!

Thanks everyone (including TPMS)... I will go buy a pressure gauge later to ensure that I've got two sources of readings apart from the compressor. I assume a Halfrauds digital gauge is OK, a quick google seems to suggest people are happy with these

Gary

[DSM2]

The thing is, whilst the TPMS does seem to be pretty accurate it's real benefit is in telling you if a tyre is losing pressure in use, IMO.

Unless I'm using the satnav, I tend to leave the TPMS display on. That way I would hope to pick up very early warning of pressure loss and might then be able to maintain full pressure and maximising the possibility of being able to repair.

[Martian O]

On a side note, how long should the TPMS batteries last? My car is coming upto 6 years old and they haven't been changed. Don't Porsche want something around £600 for a set of four?

[arcamalpha]

Personally, I think the real benefit of TPMS is that I know when the tyres have warmed up properly. Especially important with the colder mornings setting in.

[911Thrasher]

hog 1 said:

I have always found the onboard TPMS to be accurate within .05 bar against an analogue pressure guage

Same here on my 997.1 GT3 RS...i always found it super accurate, was a really good tool to have on trackdays!