How accurate is tire pressure gauge?

[trouphaz]

I have an air compressor at home with a pressure gauge that I never really had reason to doubt, but I have to set it at around 38psi to get my JLU to register it as 34. Is it more likely to be the Jeep or the compressor whose gauge is off?

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[Ohio Hiker]

Both

 

[oceanblue2019]

I have an air compressor at home with a pressure gauge that I never really had reason to doubt, but I have to set it at around 38psi to get my JLU to register it as 34. Is it more likely to be the Jeep or the compressor whose gauge is off?

Also air temp will matter, so once full let it sit a couple hours and check. Likely will come down 2 or so psi.

 

[aldo98229]

“If you have a clock, you know what time it is. If you have two, you can never be sure.” —Napoleon Bonaparte

PS - I find the built-in tire gauge very precise.

 

[Dkretden]

I have a good-quality dial gauge and the Jeep dashboard. They are within 1 pound of each other. So, either both of them are wrong or both are correct but at least they agree.

I have a smittybilt compressor. The gauge is off by something like 10 pounds. Horrible.

if I were you, I would buy a new quality gauge. That will break the tie.

 

[trouphaz]

if I were you, I would buy a new quality gauge. That will break the tie.

good idea.

 

[eck]

My TPMS sensors are very accurate, because I fill my tires with a 4-wheel Morrflate, so physics dictates that all 4 wheels are exactly the same pressure. And my TPMS readings are always exactly the same across all four.

 

[donmontalvo]

My TPMS sensors are very accurate, because I fill my tires with a 4-wheel Morrflate, so physics dictates that all 4 wheels are exactly the same pressure. And my TPMS readings are always exactly the same across all four.

Your logic is precisely why I bought a MORRFlate Quad.

I ordered it without the gauge, figured I could use my own gauge.

Well, it worked, but a bit of a PITA, so I went ahead and ordered their gauge.

 

[calemasters]

When I have to air up after a trail run, my ARB compressor adds warm compressed air to my tires. So thanks to Mr. Boyle, I have to air up to 42 psi (of hot air) so that when the air in the tires reaches ambient temperature, my tire pressure is 37 psi, which is what I normally run. Nothing wrong with my compressor or guage, it just physics. I never paid attention in English, or History, but I liked science and math. Used to be I couldn't even spell enginer and now I are one.

 

[eck]

Your logic is precisely why I bought a MORRFlate Quad.

I ordered it without the gauge, figured I could use my own gauge.

Well, it worked, but a bit of a PITA, so I went ahead and ordered their gauge.

I did the same, ordered without a gauge. I had this inflator already:

https://www.amazon.com/gp/product/B07528LFCT/

Which I highly do *not* recommend. Leaked like crazy. But the pressure gauge was fine.

I used this adapter:

https://www.amazon.com/gp/product/B0823JQL2W/

So now I have that gauge on the morrflate manifold and it works like a charm.

 

[DOOKEY]

I use the chalk test to find out how much air pressure should be in my tires. Then test with my gauge. Now I know what the gauge should read for proper inflation.

 

[J0E]

I have a good-quality dial gauge and the Jeep dashboard. They are within 1 pound of each other. So, either both of them are wrong or both are correct but at least they agree.

Ditto. I think they're more than accurate enough.

My TPMS sensors are very accurate, because I fill my tires with a 4-wheel Morrflate, so physics dictates that all 4 wheels are exactly the same pressure. And my TPMS readings are always exactly the same across all four.

Good indicator and proves they are consistent and repeatable. But they could be consistent/repeatable and be off 20% consistently.
You're right that proves they all have the same pressure.

 

[roaniecowpony]

My TPMS sensors are very accurate, because I fill my tires with a 4-wheel Morrflate, so physics dictates that all 4 wheels are exactly the same pressure. And my TPMS readings are always exactly the same across all four.

Only at the time that they are all connected by the Morrflate. But since the sun usually hits one side or the other of a vehicle, those on the sunny side will be hotter. When you inflate them all to the same pressure, but some tires are hotter than others, when the temperature of the tires all get to the same temperature, the pressure will differ, maybe significantly. So, if you can fill in the shade, it would be better.

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