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I have browed this site with "TPMS" and only to fail to get what I wanted. I am sorry to post 2 threads in two days' term. When I took delivery TPMS reading of 4 tires were not in sync. one tire had 2-3 higher reading. My SA said it was normal.

After I got my car from the dealer, even though the tech said he checked the airpressure yet the reading is inconsistent still.

Are 4 individual tires supposed to show diffrent psi? the digits on the screen keep bothering me.

so frustrating not to get any answers from the tech and SA having no choice but to ask you guys here. Shame on Porsche Korea.
 

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the 4 readings on the instrument cluster are independent of each other.

The standard answer from the Porsche folks is to adjust tire pressures based off the + or - values on the cluster until you get 0 on all 4.

I relate this because my 987.1 TPMS has been a problem since I had to put new sensors on 2-3 years ago. The left side sensors read on the cluster in the opposite positions.

I know this because I used a manual pressure gauge to check them. I asked the Service Manager if the sensors were "positional", which I knew they weren't, and described my issue. He then said "adjust based on the +1 -1 0 readings on the cluster.

No way I'm doing that, as my front left would be at 40 psi and my back left would be at 34 psi, just so I could get 0 0 0 0 on the gauge.

Anyway, I suggest you use a manual gauge and get the pressures where you want and use the instrument cluster to keep an eye on slow leaks or flat tires.

In normal driving my pressures rise 3-5 psi per tire.
 

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TPMS is a tire pressure monitoring system. It is not a tire gauge. Get a good pressure gauge and adjust your tire pressures . . . preferably when the ambient temperature is 60º F. I use a digital tire pressure gauge that reads within 1/10th of a pound. Then check the TPMS readings. The TPMS reading might or might not match the reading of your gauge. Don't worry about it. The TPMS will tell you when a tire is loosing too much air.

I like the way Mercedes does it. Adjust your tires using a pressure gauge and then set your car for that particular base reading. If your tires begin to loose air then you get a warning.
 

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"I relate ths because my 987.1 TPMSicon has been a problem since I had to put new sensors on 2-3 years ago. The left side sensors read on the cluster in the opposite positions."

I recall another thread where the back TPMS units were showing as front tire pressures and the fronts were showing as back tire pressures. A solution that seemed to work for a couple people any way, was to do a relearn on the tires using the "wrong" size and season and then reset and relearn back to the tires that are actually on the car. That procedure corrected the front to rear and visa versa problem a couple folks were having. Worth a shot for correcting a few TPMS ills I'd say. Another corrective measure to get somewhat more accurate reading was to either over inflate or underinflate by 5-6 pounds and then reset pressure to the desired amount. That seemed to work for a few folks who were getting pressure reading that were blatently incorrect. Good luck.:cheers:
 

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TPMS is a tire pressure monitoring system. It is not a tire gauge. Get a good pressure gauge and adjust your tire pressures . . . preferably when the ambient temperature is 60º F. I use a digital tire pressure gauge that reads within 1/10th of a pound. Then check the TPMS readings. The TPMS reading might or might not match the reading of your gauge. Don't worry about it. The TPMS will tell you when a tire is loosing too much air.

I like the way Mercedes does it. Adjust your tires using a pressure gauge and then set your car for that particular base reading. If your tires begin to loose air then you get a warning.
That is a good approach...simple and intuitive. Porsche's TPMS is neither.
 
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It's very common to see identically-inflated tires read +/- 2 or 3 PSI away from each other on TPMS. It is not a precision instrument by any means. (Well, it is, but it 'precisely' measures a lot of things besides tire pressure -- e.g., the difference in temperature from one side of the car to the other because of the sun's position in the sky.) Don't worry about it.



It took a long time for me to stop checking both oil and TPMS obsessively but I'm much better now.
 

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Discussion Starter #7
It's very common to see identically-inflated tires read +/- 2 or 3 PSI away from each other on TPMS. It is not a precision instrument by any means. (Well, it is, but it 'precisely' measures a lot of things besides tire pressure -- e.g., the difference in temperature from one side of the car to the other because of the sun's position in the sky.) Don't worry about it.



It took a long time for me to stop checking both oil and TPMS obsessively but I'm much better now.
Thank you for letting me be less apprehensive. I once had a flat tire on the highway and made 270 hitting the guard rail that i am always be paranoid about tires.

What I am worried is if the discrepancies get wider and i am warned with the false warning leaving me callous and get to disregard the warning.


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Discussion Starter #8
TPMS is a tire pressure monitoring system. It is not a tire gauge. Get a good pressure gauge and adjust your tire pressures . . . preferably when the ambient temperature is 60º F. I use a digital tire pressure gauge that reads within 1/10th of a pound. Then check the TPMS readings. The TPMS reading might or might not match the reading of your gauge. Don't worry about it. The TPMS will tell you when a tire is loosing too much air.

I like the way Mercedes does it. Adjust your tires using a pressure gauge and then set your car for that particular base reading. If your tires begin to loose air then you get a warning.
That makes two of us. Tpms digits make me think tpms is more accurate than merc and bmw but the discrepancy of the tpms reading leaves me dubious about the accuracy.


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