Accuracy if tire Pressure gauges rant
 

Who Knew?
Accuracy of tire Pressure gauges.
I had a full-blown, fully bonafide, lettered engineer tell me one time that pneumatic pressure gauges were inherently accurate.
Many, many years ago.
I took his word for it.

I was just out measuring tire P on a vehicle that demands within a pound or so.
Guess what?
I was looking for 50 spot on
Out of six gauges, three read around 50
The other read 60 to to 64 .
Three read 10 to 14 lbs high, OR, the other three 10 to 14 low, and I don't know which is correct.
Three are regular dial gauge style, the other three are just the retracting stick style .
One is a 30 dollar gauge I bought years ago.
None read exactly the same.
NONE.
Needless to say, this is sort of an eye-opener!
A BFD !

Yes tires dead cold.

Gauge recommendations?
Edit-doing some research here--Most universal gauges are junk !
Like I said, I had no idea......presumption....
it looks like 70 bucks are required to get a "gooder" one?

Longacre .

Forget how it's spelled..but "bourdon tube" is the key. Yes, the more expensive dial gauges have them. I'm still using the one bought off a snap-on truck decades ago...was made in USA then. Today I notice not. Motometer makes a gauge popular among the drag race set.

What vehicle requires 50 PSI ? just curious

Same experience overall. Settled on a pricier one ($100 or so) that matches what my car's TPMS thinks it is, give or take 1 PSI so we're good. In my experience the cheapo digital ones are totally inaccurate.

Interesting video here...

https://www.youtube.com/watch?v=Uzo_2g8oCzU

We rented a car for a mad dash to Dallas and back in rush hour traffic. On the way to my house I noticed the ride was awful. The tire pressure system indicated all normal. It was a Fiat as I remember. It was just a cheap rental.

I whipped out my gauge and it just pegged the gauge. I let a lot of air out, and still bang, pegged out. It took forever to get to the proper pressure. Evidently the car rental place uses that pressure monitoring system to check tire pressure. I bet that tire had triple the max inflation. I was happy to turn it back in.

You can pick up a inflation air fitting and join it to a proper air gauge and make your own, depending what you want to spend on the gauge more accurate then most preassembled.

Deschodt, most HD pick up trucks take up to about 80psi.

It is very unlikely that any measuring device you own is calibrated properly.

A cheap tire gauge? Nope.
An expensive tire gauge? Maybe. But not if it's old.
A sweep style meter? No.
Torque wrench? No.
Vernier? Probably okay.
Micrometer? Likely okay.
Ohmmeter? Likely no.

You should not be surprised.

Back when I raced karts and we were running around 7 psi where a 1/4 psi made a difference, I didn't trust my 0-15 psi dial gauge so I gathered up about half a dozen gauges from fellow racers. About half of them read the same so I calibrated off that but it was still surprising how far off many of these expensive low pressure racing gauges were.

Here's what I would buy. Big armored dial with a bleed valve. The idea is to measure using only 1/2 the scale for best accuracy.

http://www.amazon.com/Moroso-89595-Gauge-Garage-0-100/dp/B01LZOWB10/ref=sr_1_29?crid=34ORL8E0OUTBK&keywords=moroso+tir e+pressure+gauge&qid=1561056921&s=automotive&spref ix=moroso+tire+%2Cautomotive%2C184&sr=1-29

http://forums.pelicanparts.com/uploa...1561057168.jpg

No one (uncalibrated) device should be considered good. Period.

More likely the Yahoo at the rental car place just put as much air in the tires as the compressor would produce...in an effort to not have to mess with the TPM light and he wanted it to last 6 months or more before he'd have to look at it again.

I read those pencil type that you get free from discount tire were on average the most accurate. Ok this was an Honda ody club forum so not sure where they got it from

I'll second longacre.

Yup.

Their pro analog ones are probably best, but I've had this one (pro digi 0-60psi) for 20+ years and it is still pretty darn accurate (as compared to a few different higher-end gauges and multiple Discount Tire $$$ air stations):

http://forums.pelicanparts.com/uploa...1561062262.jpg


YMMV...

I sold pressure gages for years, Wika, Marsh, Hennie and others. If you want a gage to read in the 50 # range get a gage that measures up to 100#. Mid range is the best accuracy reading. We always said that if you have only one gage in line you have your doubt, two gages in line you have an argument and three gages you have a law suit.

The man with one watch knows what time it is. With 2 watches he's not sure.

For what it's worth, I just visited the snap on website. They no longer offer a gauge like mine.

At a hardware store a while ago, I noticed a bunch of thermometers on display.
Pretty wide range of temps indicated, all sitting there side-by-side.
If I needed one, I'd find the average and buy the thermometer with that reading.

I destroyed a rear tire at recently repaved track. My nice longacre digital was reading about 3lbs high. Went with a motion pro dial that checked right on with the tire vendors calibration rig. Also, recalibrate often. Bouncing the gage down the highway in your trailer to the next track, things can change.

Between myself and the guy I share shop space with, we have at least a half dozen tire gauges, ranging from moderately priced to expensive. One day, I wanted to know how accurate my regular gauge was. We put all of the gauges on one tire and 4 or 5 all agreed w each other. One or two read different. The ones that agreed w each other are accurate. They couldn’t all be off exactly the same amount in the same direction.

Have you ever heard the old adage about motorcycle helmets "Wear a ten dollar helmet if you have a ten dollar head"? There are some things that you get what you paid for. I've been told that the wider the range, the less accurate the gauge will be. To me, for most purposes, I need relative accuracy. Once I determine what the pressure should read on a particular gauge, I can measure if the pressure has changed on that same gauge. A man with one watch knows what time it is. A man with two watches is never sure.

Now I have another thing on my to do list. Check my gauges relative to each other.

A couple of my gauges are not low end, but none of them read the same.

To have a gauge read ten lbs low for a 50 lb tire is a very dangerous thing.
This might explain a lot of mine and other people's tire problems.
presumption.......never a "gooder" thing.

This is the one I carry around. Like I said, 100% accurate as measured against 5 other good tire gauges:

https://ktmtwins.com/products/accu-gage-60-psi-gauge

when different types of gauges were tested, the digital readout ones were more accurate

not surprising as they use an electronic device similar to a load cell to measure pressure, which is easy to manf. nowadays (not a spring like the analog gauges)

IDK, I will take your word for it , ..but I am transposed to the digital crap...in some respects.
The few digitals I have tried were dam hard to get into inconvenient areas.
Old dog.

Weird, I'm surprised that anyone thought that they were terribly accurate. I've generally got a few kicking around. I occasionally will compare 3+. Once I've compared 3 or more, I've got a pretty good idea of what I'm comfortable with. The TPMS in my Boxster generally reads the same as my dial gauge or not more than 1psi different, and my various gauges all read practically the same (within 1 psi) so I'm good. My car seems to perform about the same in my normal driving in a range such that a psi difference doesn't matter to me.

calibrate a nice fun to use big analog gauge against a digital one

a spring is constant within it's working range, so you'll be fine

I'd start with at least 3 gauges unless you've got one that's certified as being calibrated.

Even a digital gauge can be wrong.

Ranges vary a lot. I raced Formula Vee for years. For what it's worth, all of the folks in our pit area used Longacre analog gauges. I've had mine for years. We ran pressures in the high teens. That gauge tops out at 50psi I believe. My truck and old motorhome run pressures in the 70psi range. I had to buy a different gauge for those vehicles.

If it is 4WD:
Make sure all the readings are the same.

I just check my new truck tires today. First with a cheap Kobalt air compressor with a digital gauge and then my Blue Point gauge. The Kobalt was 2 psi high. I’ll check with my Longacre tomorrow.

Edit: The new tires ranged from 32 to 38 psi. Looks like they don’t really check them.

I had a nice dial style gauge a few years ago and used it for everything. I was having issues with the TPMS light on my wife’s van, it would trigger the light with the tires at about 35 psi, if I bumped it up slightly it shut off the light. I was about to get new sensors but first had the bright idea to compare the 5 gauges I had around the house, my nice dial style gauge was reading about 12 psi high. So every vehicle in my garage had under inflated tires. Now I compare several gauges but would like to get a good reliable one.

I have a Joes Pro 0-60PSI with hold valve. Very rugged. $50

http://forums.pelicanparts.com/uploa...1561173673.jpg

Whichever you buy, take a wheel to a reputable tire place that gets their's regularly calibrated. All the places I know of do. Then test it against your one. And if yours is out just remember it "reads 1 psi too high" or whatever.

If you're not lifting a known mass in a vacuum tube connected to the tire, you don't know what the actual POUNDS PER SQUARE INCH pressure is.


That being said, I just want me $40 dial gauge to be consistent, so that I'm correct left to right on an axle. If I'm too low or too high, I can figure that out driving, but left to right is hard.

Jeez one more thing to worry about. Thanks interwebz.

I'll get around to checking all of mine some day. What kind of vehicle do you drive that needs tire psi to within 1? That's a stupid crazy margin. You driving Pirelli F1 tires this weekend at Paul Ricard?

"1" isn't cutting it nearly fine enough these days on a race car. Even Nascar guys need to read a half pound accurately.

I have one of these and like it a lot, but can't vouch for it's accuracy (could just be a very fancy guessing device). Of course, Burner won't see it because I am on his much crowed about, ignore list for being, "too stupid". :D

https://www.amazon.com/gp/product/B07GCS9ZCM/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1

https://images-na.ssl-images-amazon....L._SL1001_.jpg