TPMS ACCURACY
#1
Instructor
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Join Date: May 2004
Location: Denver
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Suddenly my TPMS says -4 warning on tire pressure. I measured all tires with two accurate (racing analog and a digital) gages and they show on all tires that the TPMS reading is 8 pounds less than the actual tire pressure.
The dealer says that PCNA has instructed them to use the TPMS readout to fill the tires, not any gauges. This would cause the tire specifications to be exceeded (rear full load would be 52 pounds when TPMS indicates 44).
Has anyone heard of such instructions to the dealers? Seems that PCNA would be buying itself a huge liability in case of a blowout plus the car would ride like a no shocks rock. Thanks.
The dealer says that PCNA has instructed them to use the TPMS readout to fill the tires, not any gauges. This would cause the tire specifications to be exceeded (rear full load would be 52 pounds when TPMS indicates 44).
Has anyone heard of such instructions to the dealers? Seems that PCNA would be buying itself a huge liability in case of a blowout plus the car would ride like a no shocks rock. Thanks.
#2
Three Wheelin'
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I don't think you are to use the TPMS for that purpose. I believe it states something like that in the owners manual. You may want to look it up and show it to the dealer. My TPMS is off when compared to my gauge. I would go with the gauge reading.
#4
Drifting
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Mine reads about 2 psi lower on all four tires than what my gauges indicate, but I am not getting alarms since the 2 lb difference is within the allowed variation in the computer.
#5
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If TPMS on the p-car is anything like the Benz the actual reading is not pertinant. All it cares about is changes in tire pressure from the time your re-synchronize it and effectively tell it what the "normal" pressure should be.
Having said that the TPMS in my Benz is spot on with guage readings.
Having said that the TPMS in my Benz is spot on with guage readings.
#6
Drifting
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Originally Posted by boolala
If TPMS on the p-car is anything like the Benz the actual reading is not pertinant. All it cares about is changes in tire pressure from the time your re-synchronize it and effectively tell it what the "normal" pressure should be.
Having said that the TPMS in my Benz is spot on with guage readings.
Having said that the TPMS in my Benz is spot on with guage readings.
However, the TPMS on the 997 appears to have reference values for tire pressures in the computer based on full or partial load of the vehicle, and size and type tires (summer or winter). The computer compares air pressure as given by the TPMS to the values in the computer and will alarm if the "actual" values as given by the TPMS are not within a specified variance of the values in the computer. Therefore, if the TPMS is not accurate, it can cause alarms if tires are inflated to the "correct" pressure as measured by a good tire gauge.
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#10
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I've had the exact same problem. In my case my gauge reads 3 pounds higher than the tpms. I finally just increased the pressure in the fronts to stop the alarm from going off so now i run 36/39.
#11
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#12
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#14
Rennlist Member
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Tried post #13 from here https://rennlist.com/forums/997-forum/377294-tpms.html and it has worked...so far!
#15
Nordschleife Master