If you sort through them carefully, McMaster has some reasonably priced NIST certified gauges. You could probably build yourself a very accurate tire pressure gauge for ~$100 - or less if you took the hose and valve from an old gauge.
Here's one for example, accurate to +/- 1%.
https://www.mcmaster.com/3543K21

We need calibrated pressure gauges at work. We buy new ones every other year - it's less expensive than getting them calibrated by an outside vendor.

At my previous job we had test gauges all over the plant that needed to be calibrated. We had our own, in house metrology lab. They calibrated measuring tools, pressure gauges (deadweight), thermometers and scales.

That was pretty handy for my personal stuff.

My digital and analog gauges haven't been checked in years. They do match each other and they exactly agree with the TPMS on two cars, so I think they are good enough for my purpose.

ok, page 5 so I'll say it...

Nitrogen

Still loses pressure but at a slower rate.

High purity nitrogen?

yes, high purity with all the isotopes lined in little rows

Yep, the Ashcroft dial looks like that, but only goes to 60psi, has a rubber cover and bleed valve and line with end to hook on tire valves.

My BS meter? Likely OK...I'm never surprised tho'

That one may be calibrated for life. Or it may me be beyond repair.

^^^^ It's actually quite binary....an idiot light!

O reading = No BS
It moved = BS ;)

Now GOML....

I have a few tire pressure gauges that I’ve accumulated over the decades lying around and I noticed two of the gauges were giving me wildly different readings, and none of them totally agreed. I didn't know which ones were right, so I got a new Joes Racing tire pressure gauge because it’s supposed to be the gold standard of tire gauges.
I rounded up the gauges that I have and compared them to each other and the TPMS on the right rear tire of my Volt to try to find a consensus. For what it’s worth, here are the results:

TPMS – 38 psi

Gauges, Left to right:

AMFLO - 38 psi

Accu-Gage – 40 psi

CH – 35 psi

Accu-Gage – 38 psi

Joe Racing – 40 psi

Milton – 40 psi

Silver stick – 34

Blue stick – 40

http://forums.pelicanparts.com/uploa...1622827821.jpg

Consumer Reports has your answer

Buy a gauge that can be calibrated. There are companies that calibrate things, i.e. torque wrenches, tire gauges.... Request your gauge be calibrated to the area you usually measure, like 30 lbs on a 0-60 gauge. What's accurate at 20lbs. might be off at 40lbs.

Remember these? Used to come in the glove box of every new 911. Then the leather case became a cheesy black plastic one, then no more TP gauge.

http://forums.pelicanparts.com/uploa...1622919575.jpg

^ on one of these tire pressure gauge threads, I did a comparison between one of the VDO gauges, an Italian made analog tire inflator, the Intercomp digital calibrated gauge, and the Steelman digital tire inflator.

I found that the two tire inflators are very close, and they agree with the Intercomp within less than 1 psi. The VDO gauge was way way way off.

My friend bought a Longacre gauge at the track last weekend. It wouldn’t work on either of our cars. He went back to the track side vender and they tried another gauge on a third vehicle. It didn’t work either. Maybe everyone was using it wrong. 😳

I used my trusty gauge all weekend. Set my tires at 29 cold and when I came in, they all read 31, except the left front was 35. Tire wire at the edge was all uniform.

I’ve read a tire pyrometer is best, but needs to be used at the pit to be accurate.

It looks like the $28 JACO digital (dial type) is worth a look

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my car has a built in tire pressure gauge.
if the pressure gets too low,
the light on the dash comes on.
All I have to do is pump the tires up for 5 or 10 seconds
and the light goes out.
problem solved. ;)

So does mine.

http://forums.pelicanparts.com/uploa...1725826604.jpg

I never ever thought there would be so much inaccuracy in a simple gauge until it happened to me.
Project Farm was pretty informative! (and proof)
As tires and cars get more and more finicky this becomes more and more of a problem.
Now I don't trust my "Joes",
I never ever thought I would say this ...
But I am going to HF to Buy a Merlin, and or somewhere and get Eatenwolf and Jaco!

Thanx for the links!