Mike in CA

Yes, same here.

hpowders

Measured my cold pressures this morning: 35 psi, front tires, 41 psi, rear tires. Yet the TPMS gave me 31 psi, front tires, 37 psi, rear tires.

Discouraging to find the TPMS off by a whopping 4 psi!!

At least it was consistent-front and rear. Small consolation.

jhbrennan

Not unusual - I just use TPMS to check differential psi (side to side and front to rear) not absolute psi - always depend on a handheld gauge for the true psi.

hpowders

I always use my gauge and my tires are set at 2 psi "high" all around. The problem with the TPMS set at 4 psi lower is I'm going to eventually get some false alarm low pressure warnings when I am completely innocent.

gasongasoff

The TPMS readout on my 2012 matches my digital tire gauge exactly. But who knows what the true pressure is without a calibrated "gold standard" measurement device. Tire gauges are notoriously inaccurate.

jhbrennan

I set my tires at 34 front and 40 rear. When I start car in the morning TPMS reads 31 and 37 - I have yet to get a warning at those readings. Don't know what the warning tigger threshold is.

hpowders

Yours is 3 psi off. Mine is 4. At least my mpg readings are off by only 0.1-0.2 to my actual hand calculations.

Musclehedz101

I have a 07' 997.1 C4S Cab. After doing the following my TPMS readouts have been 100% accurate!

Step 1:
Read, Familiarize and perform post #6 from this thread but do it first thing in morning (cooler temps) and know EXACTLY the air temp in your garage before hand to adjust accordingly!

https://rennlist.com/forums/997-foru...-some-air.html

Step 2:
Next "reset" the TPMS per post #2, as described here:
https://rennlist.com/forums/997-foru...-some-air.html

hpowders

I won't bother looking at the TPMS readings anymore. Checking the tires once a month by hand with a gauge and keeping them 2 psi over recommended pressures should suffice.

gasongasoff

Why do people assume their tire gauge pressures are accurate and the TPMS is not?

http://townhall.edmunds.com/direct/view/.ef017dc/0

Some tire gauges can be off by as much as 8psi.

hpowders

That's possible too. Now I won't be able to sleep tonight.

cpbmd

Does anyone know of a reasonably priced Accurate tire gauge. I am now wondering who is right my TPMS or my $9 tire gauge from Autozone. The Autozone tire gauge reads 3psi higher than the TPMS readout.

Thanks
Constantine

hpowders

Seems I'm not the only one whose TPMS seems to be 3-4 psi "low".

gasongasoff

You can check out the tests here:
http://www.mcnews.com/mcn/technical/200511gauges.pdf
http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/eng5242
http://townhall.edmunds.com/WebX?14@@.ef017dc/11#MSG11

The Accutire digital seems like a good bet...

cpbmd

Thanks GonGoff
I appreciate the input. My TPMS has consistently read 3 psi below actual reading. I preformed a TPMS reboot so to speak and now it reads within 1 psi for the last few days. Interesting.
I am going to get an Accutire digital pressure guage like you suggest.
Have a nice Sunday
Time to take my 85yr ols mother-in-law out for her weekly Pcar ride.

Cons