xxrockmanxneoxx

i got in my car this morning and it said low tire pressure in 3/4 tires -4 psi. I checked the psi with my meter and it shows the recommended 29 up front and 33 in the rear. These are dunlop tires if that matters. SHould it be higher or do i just need to reset the TPMS

Jimmy-D

Would not hurt to reset and see what it reads after 30 min. of driving but 29 and 33 is ideal if no heat has been put in to them yet

golfnutintib

just re-initialize the tpms baseline

xxrockmanxneoxx

ok cool thanks guys

jphughan

I don't think this car has a baseline TPMS calibration. That applies to TPMS sensors like the one in the E9x M3 I had that don't measure pressure directly but instead rely on you to reset TPMS when you've set pressure properly and then just detect changes from that established baseline based on changes in wheel RPM for a given road speed. That of course means that if you reset it while your pressures are out of whack, it will remain quiet until things get even more out of whack (I suppose there might be plausibility values at the extremes to guard against this; I never tested it.) But since the GT4 definitely DOES measure and display an actual pressure value, I'd be surprised if just telling it to learn again affected the reading. Report back though!

Dr.Bill

The TPMS also takes into account the ambient temperature. If it's really hot out, it expects the pressures to be higher, etc.

xxrockmanxneoxx

This would make sense b/c in Houston it runs about 95 high and i didnt drive it for about a week then started having this. TPMS shows 30 psi in the rear but my gauge said 33 so dont know which one to believe(my gauge is 99 cent one but usually worked for all others).

jphughan

Well taking ambient temperature into account would mean that TPMS might allow your pressures to be a bit higher or lower before throwing an alarm, although even there I kind of doubt that because the appropriate action there is to actually adjust your pressures when the ambient temperature changes significantly. But even if that's true, it wouldn't cause your TPMS to show false pressure readings. That said, I always trust the gauge over my TPMS because I've noticed that certain values (like 31, 34, and I think 37) never ever show up on TPMS, and someone here suggested that the reason was likely that it was measuring in tenths of bar, converting to PSI, and then rounding to the nearest value, which I believe is correct because that theory accounts for all and only values that I'd never seen on TPMS. So I'd say set your pressure to a gauge-measured 29/33 in the morning before driving and then don't worry about it, except watch for significant changes in TPMS over time and adjust according to your gauge as necessary over the year as ambient temperatures change significantly.

xxrockmanxneoxx

cool and to clear the warnings is to a tpms reset?

jphughan

The only time a TPMS reset should clear warnings is if the car detects a tire change (such as rotating them side to side), in which case you'll get a warning about TPMS data being unavailable until you choose your new tire setup. Otherwise, if you're seeing values, a reset is unlikely to change them.

The Pope

The Pope

I don't believe this is correct because the manual suggests that the driver takes ambient temperatures into account when setting or viewing the pressures.

xxrockmanxneoxx

I recently picked up a mechanical tire pressure gauage by TireTek 60 psi. The question i have which gauge do i use as my main reference. For the Rear which should be 33 psi, my stick gauge shows 33...TPMS shows 30 and my new mechanical gauage shows 28. Which one do I use as my go to?

PistolPete

I would adjust the pressures to match the door jam numbers 29F/33R cold with the mechanical gauge then do a reset of the TPMS and see if it will get closer to the mechanical gauge numbers.

The TPMS on my old 987.1 Cayman S would always be higher than my gauge by 2 or 3 PSI so I just mentally adjusted for it when looking at the dash TPMS. The TPMS on the GT4 is spot on for me now.

xxrockmanxneoxx

Cool I'll try that