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Discussion Starter #1
Hola, very new to Jeeping and off-roading and such. Very much addicted already. After two trips (Rausch Creek and AOAA), I decided to pick up a set of tire deflators. While I was at it, I also bought a portable air compressor with a digital setting to it (http://amzn.to/2gefBxz).

They arrived yesterday and my son and I took them out to the driveway to test and set. In doing so I found that the TPMS in the vehicle is "off" by a few pounds and the gap seems to grow as the pressure goes up.

For example:

TPMS - 17psi
Analog Gauge 1 - 15psi
Analog Gauge 2 - 15psi
Digital Compressor - 14.5psi


TPMS - 39psi
Analog Gauge 1 - 34psi
Analog Gauge 2 - 34psi
Digital Compressor - 33psi

So on the low end, there's a difference of about 2psi. On the high end, there's a difference of about 5psi. Anyone know if this is normal? I'm assuming I should trust the analogs as "accurate"? In the end, I'm not sure that these variances really matter, I'm more just curious if any one else sees the same or similar.
 

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Was your jeep parked for awhile? These things are only accurate after rolling for a few minutes. I have found that I could use the display when airing up and down, but only if I'd been driving and left the motor running while inflating and deflating. For garage use, a real gauge is necessary.

Mark

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It's my impression the TPMS is highly accurate for most vehicles. I have half a dozen gauges not including the throw away pencil gauges, some cheapos and some higher end ones. They very up to 8-10 pounds between them. Two of my good ones and the TPMS are within a pound of each other. These two are also very close to right on when checking two of my other vehicles pressure. Keep in mind that one hit to the ground on most gauges will affect the reading.
 

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Discussion Starter #4
The jeep had been parked after driving home, but only for about 10 minutes. I also had the engine running while testing as I was using a 12v inflator running off the car.

I'm headed back to AOAA in two weeks and will see what my buddy has to show with his TPMS and gauges (I think he has two analog as well). Like I said earlier, this is more of a curiosity than a concern - all feedback is greatly appreciated.
 
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