Accuracy if tire Pressure gauges rant

[T77911S]

I have 2 sets of CIS gauges, both purchased at the same time (they sent me 2 by mistake and told me to keep it). at higher pressures they DO NOT measure the same psi.

I have thought about the same with a tire pressure gauge since I just bought a nice one to go racing with.

I figure its all relative. that is, if you determine 20psi is what you need for cold pressure, then as long as you ONLY use that gauge, you will never know or care if it is accurate or not. you just need it to be consistent.

[red-beard]

It doesn't matter if they are digital or analog, you will need to calibrate them against a known standard.

[KFC911]

Originally Posted by red-beard

It doesn't matter if they are digital or analog, you will need to calibrate them against a known standard.

I flatten all four tires...get a zero reading first on all....digital or analog. Tires must be cold to ensure accuracy....YMMV.

[911 Rod]

How do you calibrate a gauge?

[KFC911]

Originally Posted by 911 Rod

How do you calibrate a gauge?

If yer not setting race tire pressure....just check a new one with your four tires. I want a consistent reading....say at 35 PSI....the actual accuracy of the #...ball park close is OK enough...for me.

[911 Rod]

Originally Posted by KC911

If yer not setting race tire pressure....just check a new one with your four tires. I want a consistent reading....say at 35 PSI....the actual accuracy of the #...ball park close is OK enough...for me.

Calibrating is when you can dial it in to be correct.

[KFC911]

Originally Posted by 911 Rod

Calibrating is when you can dial it in to be correct.

I can use the super computer between my ears and get the same result...as long as it is condistent....

Calibrate me now....or calibrate me later

[red-beard]

Most good gauges have screws for changing/adjusting the zero and span. Cheap ones will not.

[KFC911]

I'm screwed

[RKDinOKC]

Don't remember the tire-gauge brand but the dial says Ashcroft on it.
It is very accurate!
My mechanic gave it to me when i started autocross. Told me accurate tire pressures are very important.

[Sooner or later]

Someone needs to do an R&R sudy....

[ian c2]

Originally Posted by RKDinOKC

Don't remember the tire-gauge brand but the dial says Ashcroft on it.
It is very accurate!
My mechanic gave it to me when i started autocross. Told me accurate tire pressures are very important.

Like this one ??




There’s a couple of ways of calibrating them . Most common being Dead weight , or a calibrated by pumping against a calibrated “base gauge “ or calibrated transducer and fluke etc
Never put my tire gauge on a deadweight , but calibrated against a crystal when new and it was dead on .
Edit : it’s a long acre btw

[wdfifteen]

Originally Posted by 911 Rod

How do you calibrate a gauge?

You would have to go back to first principles. Get a Tube with a piston in it - like a tire pump. Calculate the area of the piston, say it’s 2 square inches. Connect your gauge to the hose, put weights on the handle 100 lb would give you an accurate 50 psi.

[RWebb]

IIRC, NIST uses manometry for this range of pressures.

Here is a scientific instrument house:
https://www.coleparmer.com/p/nist-traceable-pressure-gauges/59678

I dunno what the engineers use. But I do know you can git as deep as ya wanna with this...

[ian c2]

And all this science I don't understand .
It's just my job five days a week .

[gtc]

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

[Porchdog]

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.

[RWebb]

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

Nitrogen

[Sooner or later]

Still loses pressure but at a slower rate.

[ian c2]

High purity nitrogen?