RiojaRed

I've got a digital tire pressure gauge that I'm pretty sure underreports tire pressure by 2 PSI. But I've noticed that the TPMS in my car matches its reading. Unfortunately, I can't find any of my analog gauges. Without having to go purchase another one, can one of you guys tell me if the TPMS is designed to underreport tire pressure on the 3IS?

Sasnuke

I also have a digital tire pressure gauge that measures in 0.5PSI increments.
I've noticed between the gauge and TPMS on the info screen it's possible to have a 1 - 1.5PSI difference. The TPMS seems to be lower as well.
I guess the question is, is the digital gauge right, or is the car right?
Given the margin of error (1 - 1.5PSI), I honestly don't care, once all the tires are inflated to the same PSI...I like all my tires the same and a tad higher than recommended due to the 20 inch tires on my IS.

cFoo

I have a digital gauge with .5PSI increments as well and it reports the same as the TPMS. Keep in mind, if you're not using nitrogen your readings will fluctuate with surface/tires temperature.

RiojaRed

Hey guys,

Thanks for the responses and sorry for coming back to this thread after so long. I thought I'd close it out in case someone searches for this issue in the future.

I've checked with two calibrated gauges, one at home and one at a shop, and the TPMS reports exactly the same pressure as the gauges.

Lol you know what they say, "A man with a watch knows what time it is. A man with two watches is never sure."

arentz07

I have an analog gauge, and it and my car's info screen tend to be pretty close, i.e. less than 1 PSI difference. Generally I just trust what the info screen says nowadays.