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Thanks to all who replied. Great information.

 

[MikeyA56]

Mine's jacked up. It's properly inflated, but warning is still going off. It's a relatively new issue, so it may be my sensor is bad. Will have dealer check when I bring in for service

 

[MDJAK]

My former X5's TPMS was the most temperamental thing I'd ever experienced. Once winter came around, it would always show a warning, every morning. Real PIA. Then, when I had a nail in the tire and it was down 12 psi, no warning. Go figure.

As for the Macan, never a problem. When I had a nail, I also watched the pressure going down steadily. Oh, the horror.

 

[mattc]

So what is ideal full load pressure for 20" summer tires on a 2017 GTS? One of my rear tires showed as -9 psi on my TPMS after only 10 days and 700km on the car. I added air but am concerned as the car is so new...

 

[iconoclast]

So what is ideal full load pressure for 20" summer tires on a 2017 GTS? One of my rear tires showed as -9 psi on my TPMS after only 10 days and 700km on the car. I added air but am concerned as the car is so new...

What does your manual State? Keep in mind CTP values are supposed to be @ 68 degrees. If warmer, you must adjust according to that article I linked. How many miles on the car/tire has absolutely nothing to do with what the CTP is or s/b.

 

[grim]

What does your manual State? Keep in mind CTP values are supposed to be @ 68 degrees. If warmer, you must adjust according to that article I linked.

The article is right but doesn't the TPMS automatically account for that? Pretty sure it does. If your manual sayss the tire are supposed to be at 35 lbs (example) and its 28 degrees out, it could be as low as 27 lbs. That's not right. Thats underinflated. Shouldnt it still be at 35 lbs regardless of the fact its 28 degrees?

This is why if you are in a heated garage at 68 and go out and its 28 (or 18) outside, the tires are underinflated. https://corporate.goodyear.com/en-U...n-US/media/news/As-Temperature-Drops--So-Does-Tire-Inflation-1426100392863.html

Cold Inflation Pressure (CIP) means prior to the tires heating up which could increase 5 lbs from driving. http://www.tirebuyer.com/education/tire-inflation-pressure-and-temperature

 

[iconoclast]

The article is right but doesn't the TPMS automatically account for that? Pretty sure it does. If your manual sayss the tire are supposed to be at 35 lbs (example) and its 28 degrees out, it could be as low as 27 lbs. That's not right. Thats underinflated. Shouldnt it still be at 35 lbs regardless of the fact its 28 degrees?

This is why if you are in a heated garage at 68 and go out and its 28 (or 18) outside, the tires are underinflated. https://corporate.goodyear.com/en-U...n-US/media/news/As-Temperature-Drops--So-Does-Tire-Inflation-1426100392863.html

CIP means prior to the tires heating up which could increase 5 lbs from driving. Tire pressure and temperature | TireBuyer.com

I think the TPMS should account for ambient temperature & temperature inside the tires but, only on the screen that tells you +/-. If it says "-3#" I think it is telling you to ADD 3#. I'm not sure it is always very accurate though. I always use my digital tire gage to fill tires.

I use part load for my 19" summer tires. In summer it is typically ~ 100 degree when I check CTP, so that is ~ 30 degrees more than the 68 degree standard. So my fudge factor is +6% & I have my goal summer CTP = 35F, 38R. (My winter goal = 33F, 36R since it is often ~ 70 degrees ambient) So, usually that is what my TPMS reads as I 1st depart my garage, takes maybe a couple blocks slow driving till I get a reading.

As I drive that day I typically see the HTP increase to 38F, 41R. But, when I am stopped & press enter a couple times I typically see "0" for all 4 tires meaning the pressure is correct. This is what I also see when I 1st start driving when the CTP = 35F, 38R.

In summary, when you 1st go to TPMS, it should show actual TP & (when stopped) if press the enter button on the steering wheel 2x, it shows difference from ideal taking into account temperature. You goal s/b "0." But, Unless it routinely shows > than 1# ... i would not get bent out of shape as I think it changes. You can have it "-2#" for one tire & the others -1 or 0 & 5 min later they all are @ -1.

 

[daohaus]

So I was messing around with the TPMS today and now it keeps showing that it's learning no matter how much I drive over 15mph what the heck happened?

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[daohaus]

I just posted on a separate thread but I was messing w/ the TPMS this morning and it was "learning" but did not stop I still have the warning light and on the PCM it's showing that it's still learning. Parked the car, car pooled to work, got back and started up the car again and warning light still on. Selected 20" A/S tires went through the steps and still learning. What the heck happened here

 

[iconoclast]

I just posted on a separate thread but I was messing w/ the TPMS this morning and it was "learning" but did not stop I still have the warning light and on the PCM it's showing that it's still learning. Parked the car, car pooled to work, got back and started up the car again and warning light still on. Selected 20" A/S tires went through the steps and still learning. What the heck happened here

1) using a manual digital tire gauge, put in the correct CTP.
2) reset the TPMS. To reset, choose wrong/different settings, back out of that screen with "OK" or "enter" & then... change back to correct. For you... choose 18 or 19" Summer Tires. Then, whatever reading it gives you, go back & change it to the correct 20" A/S.

If that doesn't work, call & ask dealer & maybe they have a different procedure to reset or will have you bring it in.

 

[bobblehead]

the tpms setting also has a check box of "full load". I did not check off on this box.

My 21 summer is set at 34F/36R right now. No issue or warning. I believe recommended / factory setting is 36F/39R. Way too bouncy for me on rough roads.

 

[iconoclast]

the tpms setting also has a check box of "full load". I did not check off on this box....

If Full load box is unchecked, that means "part load"
I know it is stupid. For a car this expensive they couldn't have added a box explicitly labeled "part load?"

 

[daohaus]

1) using a manual digital tire gauge, put in the correct CTP.
2) reset the TPMS. To reset, choose wrong/different settings, back out of that screen with "OK" or "enter" & then... change back to correct. For you... choose 18 or 19" Summer Tires. Then, whatever reading it gives you, go back & change it to the correct 20" A/S.

If that doesn't work, call & ask dealer & maybe they have a different procedure to reset or will have you bring it in.

Thanks it fixed itself somehow, quirky

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[daohaus]

It resolved itself, I was going mad trying to figure it out

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[iconoclast]

Thanks it fixed itself somehow, quirky

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I suggest a reset anyway. Takes a few minutes.

 

[mike916]

I just started having this problem yesterday during heavy rain storm. Gauge reads normal pressure, but warning light says 3 lbs low. I even added extra air and check with an analog gauge. Car now says 3 lbs more than it should, but it still gives warning and recommends adding additional 3 lbs. Problem intermittently clears with driving, but then comes back again.

Did you ever manage to resolve this problem? I have exactly the same problem which started during heavy rain and driving through a 30 yards stretch of standing water about 6" deep. The warning appeared right after that saying add +3 bar to the right front tyre. That was 5 days ago and the warning has appeared again 3 times since. Actual pressures of all wheels are fine. I will take it into the Porsche workshop if it continues to persist.

 

[MikeyA56]

Did you ever manage to resolve this problem? I have exactly the same problem which started during heavy rain and driving through a 30 yards stretch of standing water about 6" deep. The warning appeared right after that saying add +3 bar to the right front tyre. That was 5 days ago and the warning has appeared again 3 times since. Actual pressures of all wheels are fine. I will take it into the Porsche workshop if it continues to persist.

Yes, somehow after service, it went away. However, Ironically, this morning, I got a new message that the right rear was -4 PSI, even though it was reading correct pressure on the dash. No heavy rain this time either. These TPMS are so finicky.

 

[iconoclast]

... Is there a way to manually reset the TPMS system to recalibrate all tires?

Yes. Per my Dealer when I had issues, to reset just change the settings to a wrong tire size & type. Example, if you have 19" Summer, part load, change to 20" winter full load. Then change it back to the correct values. This forces the TPMS to reset.

 

[ARMTNBIKER]

I just measured (and topped up / deflated) with an Accu-Gage analog pressure gauge to 36 PSI front / 39 PSI rear, +/- 0.5 PSI. After a 10-minute drive, the Fill menu continues to insist I should "Top Off -3 PSI" despite the regular tire pressure window showing 35 front (both) and 38 rear (both). So the warning light doesn't match the car's own estimation of current air pressure. And neither the warning message nor the tire pressure display are particularly accurate.

I guess I will have to take her in just to figure out why the tire warning light is on. One of the front tires was a few pounds light before I started. I wonder if the warning light, despite telling me the rear passenger tire is low, really was obtaining the low signal from the passenger front tire. I'm assuming they use wireless to communicate with the car's computer. Maybe someone accidentally cross-strapped the passenger front tire sensor with the passenger rear tire pressure receiver?

TPS can be problematic on all cars
Note that in the set up u can choose heavy load

Sometimes I have to play with that....
I use 35 front, 38 rear
Good luck

 

[maxdbunny]

I used to have a Mini that the TPMS would go off all the time, to the point I thought I had a bad sensor. As it turns out, really dramatic air temp change and potholes can set the sensors off and trigger a warning. The air temp change is obvious the pothole one confused me until I thought about it. A sudden jolt could set it off I realized. I live in LA so the potholes are occasionally evil here!