Tire pressure
Thread Starter
Burning Brakes
Joined: Jul 2007
Posts: 753
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From: Clearfield Utah
Tire pressure
I use a dial pressure gage to reach a 30PSI level (cold) and DIC states that I have 28PSI - what do I believe, gage or DIC. The elevation here is around 4700ft above sea level. I don't want the tires wearing out any faster than normal.
Pro
Joined: Sep 2007
Posts: 743
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From: Papillion NE
Is your gauge "digital"? Digital is allegedly more accurate. I recall someone saying the gauge is more accurate than the DIC. I suspect the real solution rests in taking your gauge some place where you can confirm its accuracy and then check it against the DIC
Pro
Joined: Jan 2006
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From: Berwyn IL
46490 -- the problem is your altitude. The tire pressure sensor has no reference to the outside of the tire, so it doesn't know you are at 4700 feet. The dial gage has reference to atmosphere, so it is reading accurately.
Drifting
Joined: Apr 2007
Posts: 1,768
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From: ABQ NM
Here at ABQ's 5000' altitude DIC reads 2 to 3 psi less than handheld digital gauge. I use a handheld digital gauge which self-calibrates to local altitude zero psi the first time you use it. Also, in the morning, sunny-bright, tires cold, I see 3 psi difference between the sunny side and shady side of the car. After a few miles all tires read the same on the DIC.
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St. Jude Donor '05-'06-'07-'10
As has been noted your altitude in this case is the likely culprit. The TPMS are calibrated for readings at sea level and the change in altitude is causing you to be a couple of pounds less. It should be fairly consistent so you can use that as your "zero" point if you will and just adjust from there on the DIC. What I'm trying to say is that your dial gauge should be acurate in this case.
CF Senior Member
Joined: Feb 2006
Posts: 23,313
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From: Tucson Arizona
Make sure you're getting a current reading from your TPS's...take a short drive (over 15 mph) and compare warm or even hot tire pressure readings between the DIC and your handheld gauge.
I would tend to believe a hand-held gauge but not all gauges are created equally. There are some very good analog gauges and they are somewhat costly. Sears sells a decent Craftsman digital gauge for around $30 or $35 that I've found to be accurate (they claim accuracy within 1%).
It can be frustrating...I've compared pressure readings from two hand-held gauges to the DIC readout and come-up with three different numbers.
I finally tossed my cheap digital gauge and I just rely on my Craftsman digital gauge. Even having one side of your car in the sun will affect readings.
Maybe stop by Discount Tire and compare readings to a gauge they deem as being accurate.
I would tend to believe a hand-held gauge but not all gauges are created equally. There are some very good analog gauges and they are somewhat costly. Sears sells a decent Craftsman digital gauge for around $30 or $35 that I've found to be accurate (they claim accuracy within 1%).
It can be frustrating...I've compared pressure readings from two hand-held gauges to the DIC readout and come-up with three different numbers.
I finally tossed my cheap digital gauge and I just rely on my Craftsman digital gauge. Even having one side of your car in the sun will affect readings.Maybe stop by Discount Tire and compare readings to a gauge they deem as being accurate.
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From: Life ain't no dress rehearsal, are you gonna wait to get your toys til AFTER you have a heart attack?
So, what you are saying is that the TPMS is measuring the absolute pressure in the container (the tire) relative to sea level (~14.7 psi) and the gauge is measuring the differential pressure at 4.7K ft. where the atmospheric pressure is < 14.7 psi? Are you also inferring that if someone were to drive the car down to sea level, let the tires cool to the same temperature that they were at 4.7K ft. and use the same digital pressure gauge the pressure the TPMS shows and the pressure the digital gauge shows would be the same?
Last edited by PappyTinker; Jun 19, 2008 at 10:35 AM.
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St. Jude Donor '05-'06-'07-'10
So, what you are saying is that the TPMS is measuring the absolute pressure in the container (the tire) relative to sea level (~14.7 psi) and the gauge is measuring the differential pressure at 4.7K ft. where the atmospheric pressure is < 14.7 psi? Are you also inferring that if someone were to drive the car down to sea level, let the tires cool to the same temperature that they were at 4.7K ft. and use the same digital pressure gauge the pressure the TPMS shows and the pressure the digital gauge shows would be the same?
http://www.tirerack.com/tires-techpage-1/167.shtml
Pro
Joined: Jan 2006
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From: Berwyn IL
So, what you are saying is that the TPMS is measuring the absolute pressure in the container (the tire) relative to sea level (~14.7 psi) and the gauge is measuring the differential pressure at 4.7K ft. where the atmospheric pressure is < 14.7 psi? Are you also inferring that if someone were to drive the car down to sea level, let the tires cool to the same temperature that they were at 4.7K ft. and use the same digital pressure gauge the pressure the TPMS shows and the pressure the digital gauge shows would be the same?
Terry
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From: Southern Utah
Advanced
Joined: Jan 2005
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From: Alta Loma CA
The TPM sensors display in whole numbers. A quality analog (dial) gauge will typically show increments to 2 tenths of a pound. So when one makes the presumption that a digital pressure indicating device (which the TPM sensors are) is more accurate, the question is at what pressure does 30 psi become 31 psi? Is it at 30.5 psi? Or at 30.8psi? The answer is "it depends on the display programming of the sensor and indicator". I use a quality analog dial gauge for my tire pressures. And yes, it's calibrated to a second tier NSTL standard. My gauge and my TPM sensors match, I live at about 800ft. elevation (not altitude).
I know, this sounds picky, but the topic is accuracy.
grins,
Don
I know, this sounds picky, but the topic is accuracy.
grins,
Don