Tire Pressure Gauges - Analog Vs. Digital

Tire Pressure Gauges - Analog Vs. Digital

The purpose of my inquiry, after two months of experience with two digital tire gauges, is not to find out which brands of gauge are better than others, but rather, to find out which type(dial face vs digital) you feel:

  1. Consistently gives the same result over and over again.
  2. Has the best absolute accuracy(against a known reference gauge)

One of my two digital models, a DIYCO Pro, takes 3-5sec. to reach a reading. After dumping it(releasing the air from it when it is removed from a tire), and valving that same tire again two or three more times, I get different readings as much as 2psi apart. IE: first read: 33.5psi, second read, 32.9, third read, 33.2, etc.

If I set all my car's tires to exactly 33.0psi, how do I know all four are really exactly 33.0psi(according to a theoretical reference gauge)?

With dials, If I keep taking readings, the indicated pressure goes down just a hair with each successive reading, but, I get a reading right away, and bleeding down is fast and no nonsense compared to the digitals, which "slowly climb back"from a bleed: 32.8...32.9.........? .....33.0! Whew, finally!

Which do you prefer: Decimal precision of a digital tire gauge that you must wait a few seconds for, or, no- nonsense, quick reading of an analog? And is either really any better?

Reply to
thekmanrocks
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I have about 20 different tire gauges, probably 3 of those will read matching pressures, most are within 1-2 psi. I;m not real worried if the tires are 33psi, or 35 psi, as long as they all read the same on the same gauge. I love the Journey as it shows PSI on the TPMS display. With the car setting in the shop and cold tires, I can check them and find each one is at 36 psi. Then look at the display and see it showing every tire at a different pressure, both higher and lower but usually within 2 psi of the gauge.

As for which is better, it's a crap shoot unless you have it tested and calibrated regularly.

Reply to
Steve W.

Steve W.

I guess more broadly: mechanical/analog gauges more directly measure the tire pressure, vs digital models, which probably use some algorithm to determine the pressure?

Again, I've spent two months with more than one digital tire gauge, and after experiencing both their good and bad sides, I'm actually longing for the simplicity of an analog gauge again. I'm hoping the $40-something I'm paying for my yet-to-arrive Longacre Analog 'Deluxe' will show improvements in quality and particularly consistency of reading, compared to the $10 or so I paid, 5 and 10 years ago, for Accu Gage's S60X dial-face model that was my go-to for ten years until recently.

Reply to
thekmanrocks

- show quoted text -

__________ ^This!^

Consistent, repeatable readings.

Reply to
thekmanrocks

No algorithm needed. They just translate a voltage signal from the pressure transducer into a digital value. Or they could use a variance from a reference voltage. Either way, there is no algorithm, just a translation from one type of signal to another.

Reply to
Xeno

____________ Thank you for that explanation, Mr. 'Plains Dealer'!(BTW that was the name of a midwestern newspaper, not sure if they're still in print).

Makes sense, and an interesting point: Both my Longacre and DIYCO digital gauges read HIGH(about 1psi) compared to my Accu Gage S60x dial, and two garages I brought them to for reference. We'll see how my Longacre dial gauge compares to the rest of this fleet, and the garage.

Reply to
thekmanrocks

Most of the digital gauges use a version of a resistance pressure transducer, like an oil pressure gauge sender. As the pressure changes the resistance changes and gives you a reading.

The catch with an analog gauge is the tube flexes every time you use it and over time it can weaken.

If they show a spec for the ASME B40.1 or ASME B40.7 standards it can give you a better comparison. Most of the better gauges out there run in the B area, IE 2-3% error across the scale with the best readings in the middle of the dial. You can get hyper accurate lab grade gauges, but they are $$$$.

Reply to
Steve W.

Reliability/repeatability varies a lot so I have no opinion but of non-digital gauges, there are spring type (like Milton, Tech) and there are actual Bourdon tube type (AccuGauge, Kingsbridge). Even between those I'm sure some china factory could screw up accuracy of a Bourdon tube so technical design and actual product may be very different.

Reply to
AMuzi

Amuzi:

This

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just arrived in the mail today, and I am most impressed by its heft and construction quality! Compared to my Accu Gage and my digital Longacre, the head unit itself is HUGE - and this is just the deluxe, not the pro version! I would say slightly smaller than a standard tennis ball. Thick red hose, 17" long, solid chuck, this gauge seems almost overbuilt for its purpose in life: Accurately dialing in cold tire pressure on all four tires of a motor vehicle.

I went out and checked the pressure of one of my tires with it, and it seems to go effortlessly about returning a reading. And yes, it holds the reading solidly, until I dump it via the bleed valve - which takes about 2-3seconds of holding in the bleeder button. Plus, it glows in the dark for those who need to check a tire out on the road after dark.

I called Longacre Racing to find out what kind of design it is(Bourdon vs spring) and the gentleman who answered the phone(right away, no menus "please press 1" crap by the way)confirmed it is Bourdon, as all their analog gauges have been for over ten years. What he was unable to confirm with me was the ANSI(American National Standards) grade this gauge would fall under - AA <0.5%, A <1.0%, B <2%, etc. Never even heard of the department.

He did say that the Deluxe is a "3-2-3%" gauge as far as accuracy is concerned: 3% accuracy below 20psi and above 40psi, and 2% from 20-40psi. So for a required reading of IE: 35psi exactly, that's plus/minus 0.7psi. For a reading of 50psi, that's an error of 1.5psi.

Supposedly their basic digital gauge is 0.8% accurate, or plus/minus 0.28psi at our example, 35psi, with resolution down to 0.2(one fifth) of 1psi. I just don't like waiting 2-3 sec. for an exact reading!

So I'll see how my new Longacre deluxe analog hold up with regards to repeatability.

Reply to
thekmanrocks

If you are looking for high accuracy, don't you need to have periodic calibrations against a traceable NBS standard, to ensure it hasn't drifted?

Some lab equipment has stickers to show it is up to date.

Reply to
Hank Rogers

Hank Rogers:

Calibration every 2-3 years might be enough for a gauge used by a consumer, esp. if they invested $50 or more in the gauge. I paid mid-$40s for the aforementioned Deluxe Longacre, and I'd like to have it checked new. Would probably hold its setting for 4 years the way I coddle my gauges! :D

Reply to
thekmanrocks

Hank Rogers addendum:

Where DOES one get a decent gauge calibrated?

And alsom who in this day and age still has a 'master gauge' to check one's own against?

Reply to
thekmanrocks

Aside: I went to work in QA for a place that required everyone to check their ground straps each day against the <thing> sitting in the corner. Months later I discovered that the <thing> itself wasn't grounded.

There's always something waiting to bite you in the ass.

Reply to
The Real Bev

The Real Bev:

RE: "thing in the corner"

Did you get knocked across the room? :D

Reply to
thekmanrocks

No, just seriously pissed off. It had an official name, listed in the procedure manual, but that was quite a while ago.

I think the ground connections at the workstations were actually grounded so the testing station wasn't actually useless (if the strap made connection to the test station it ought to connect properly to the connector at the workstation, right?), but I wondered if the <thing> had EVER been grounded.

Not my circus, not my monkeys!

Reply to
The Real Bev

Longacre Racing #52-52003 Deluxe analoge Tire Gauge:

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  1. Unboxing - Typical Longacre retail hook-top clear shell, with card in back, gauge face surrounded by its own hose. Two foam spacers inside to keep things stationary, one with a slit containing the supplied optional brass ball-chuck. Which, by the way, weighs more than half of what my Accu Gage S60X does! These guys don't play regarding build quality!

  1. Use. Last night, I overinflated my car's tires to about 35psi. Early this morning, I bled them down, from 34psi to vehicle recommended 32. Valve smartly attached to tire valve, but I noticed something different with this gauge: the needle moved slower up to the reading, not 'snapping to' as with my other clock face gauges. This has to do with the "shock absorption" Longacre built in to their Bourdon tube mechanism, to avoid over-stressing the mechanism.

  2. Bleeding: Bleeding is commensurate with how hard I pressed the bleeder button on this gauge. No surprises, like suddenly finding myself 2psi BELOW my target. The needle drops down 10-15psi during bleed, then slowly returns to the newest reading.

  1. Readability: As with any analog dial gauge, just be facing it square on, so you'll hit your mark every time.

The gauge, as true to literature, holds the last pressure indefinitely. But, you should dump it(bleed out that last reading) before storing it, to relieve stress on the inner movement, just as you would dial down a knob-style torque wrench before storage.

  1. Accuracy/Repeatability: The Deluxe reads half psi higher than my Accu Gage, and 1psi lower than my Longacre Basic Digital(again: get what you pay for!), and about 0.2-3psi lower than my DIYCO Pro Digital backlit. And yes, I can come back again and get the same reading on a tire. The ultimate verdict on accuracy will be when I take the Deluxe to a garage and check it against one of theirs.

So it looks like my new 'go-to's are this Longacre Deluxe Analog, with 1 and half psi hash marks on its big 2.5" dial, and the DIYCO digital, resolving down to one-tenth psi, or bar or kPa if you prefer.

I suspect both of my digitals read a tad higher owing to their being electronic in nature, and battery operated, and to no other factor. I just have to be more careful using them, that Longacre digital. Set my tires to

34psi indicated with that one, which will read 32psi on the Accu Gage, and 32.5psi on the new Analog Longacre, and 33.0 cold on the DIYCO Pro.
Reply to
thekmanrocks

UPDATE Re: Longacre #52003 - 'Deluxe' Analog Tire Gauge

I took the above, plus an older Milton shirt-pocket gauge that I found in my garage and cleaned all the grime off of, to my local mechanic to cross-check against his Astro 3018(? looks like one anyway) inflator gauge.

Results:

My Honda calls for 32.0psi cold in its tires.

After driving just under 1mile to my mechanic's:

Astro 3018 showed my right front as 32.5psi 3x.

Longacre #52-52003: Approx. 32.6-7 psi, twice. 0.2psi over Astro.

Milton shirt pocket/pencil: 34.2-3ish, twice. 1.7ish psi over Astro.

So for absolute accuracy, the Longacre 52003 dial-face was worth the $45+ I invested in it. No need to mentally compensate with that one!

I know that my digital Longacre reads one full pound/sq. inch over the analog Longacre, so 1.4-psi compensation required.

My digital DIYCO D1 Elite reads about 0.3psi above the analog Longacre, or about half-psi above the garage Astro. So 1.0psi compensation there. My only pet peeve with the DIYCO is it takes 3-5sec. to get a reading: 31.9.....32.1...

32.3! Batteries new in both digital gauges.

So: Longacre #52-52003 Deluxe analog is my home reference, with the DIYCO in second place.

My Longacre Basic Digital reads quickly, but is 1.4psi higher than the garage's Astro, but I must remember to compensate.

My old Accu Gauge: about a hair below the Astro 3018, but better to slightly over than underinflate.

The Milton pocket pencil? EMERGENCY use only, at nearly 2psi over garage. The index rod slides so easily on it and lots of wiggle, so I suspect it's really old and probably worn out.

I hope the above reference tests will guide others' future tire pressure gauge purchasing decisions!

Reply to
thekmanrocks

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