i like filling my own air pressures, and making sure they're accurate given the temp outside. i have one of those cheap air pressure gauges that you can buy at autozone. i thought i filled my fronts at 33 and rears at 39, but according to the TPMS, they're at 36 and 43! i took out a little air pressure, but left it a little above 33/39 because i'm taking a trip this weekend and there's gonna be 3 people in the car.

what gives with the discrepancy between the two?


should i go with the TPMS readout? also, can anyone recommend a more accurate air pressure gauge? i don't know much about them

thanks in advance!

 

My 09 997S TPMS readings are right on perfect. I have a high end Longacre air gauge and it and TPMS agree.

I bet your Autozone gauge is wrong.

For around $50 you can get a digital Longacre gauge...or even the digital Griots Garage gauge that reads in tenths is accurate.

 

I have an accurate racing gauge - verified against three other gauges - TPMS consistantly reads 4 - 5 psi low - major PITA. I had the car in to the dealer when still under warranty and was told that that's this just the way it is. I would love to know if there is a Porsche spec. for TPMS accuracy - I have to run my tires several psi high to keep the warning lights off. Arrghh...

 

I have a Moroso racing gauge with a bleed valve, and TPMS always reads a few lbs higher. I haven't resolved the issue yet either, but I think the moral of the story here is that TPMS is frequently wrong.

 

It seems the 997.2 TPMS is far more accurate than the older systems. My '09 C2s is spot on. My '07 997.1 system never agreed with the gauges. Use a quality pressure gauge(s) as primary. I'll periodically verify the gauge's accuracy with a calibrated pressure panel.

 

I thought I read in the Owner"s Manual that the TPMS is to be used as a reference and that a hand held gauge should be used when checking and adjusting air pressure.

 

the tpms on the 997.1 are +/- 3-5 lbs. they're typically very precise but not very accurate - they're consistent how far they're off.

the 997.2 seem to be a new generation, much better.

in any regard, the tpms is really used to detect delta's, not absolute pressures...

 

My TPMS (997.1) reads 1 psi high, consistently, compared to my gauge.

 

++ on that........same thing. My TPMS is in-sync with my Longacre.

 

Kaama, I've learned that our .2 cars TPMS is very accurate but the .1 cars TPMS is not.

 

My 2008 C2S is always 3 psi low on the TPMS......I use an accurate digital gauge to check tire pressures. In my book the TPMS is just a reference to monitor the tire pressures in operation.

 

The TPMS on my 08 C2S reads consistently 2 lbs low, compared to multiple gauges I have.

 

IIRC, the TMPS sensors changed in '08 and then again in '09.

unfortunately, you can't upgrade them because they're not all compatable with PCM

 

My TMPS is consistently 2-3 lbs low. After the tires warm up, I get to 33/39.

 

Just checked mine and TPMS shows exactly 3# lower than my digital guage.