3 air gauges don't agree

[chriscowles]

I have the TST TPMS that came with my Rockwood, a Taiwanese analog dial air gauge and the analog dial air gauge on my Viair air compressor. None match. The difference is only a few pounds between them but which do I trust as a source of truth?

If relevant, the target pressure is 65#.

[MevetS]

The suggested method would be : https://asq.org/quality-resources/gage-repeatability

[KyDan]

Consumer Reports recommends these 2 as their top choice for
both accuracy and reliability.
Accutire MS-4400B

and the

Accutire MS-4021B
both around $10 more or less.


FWIW I have a 4021B and after several years (like maybe 8 or so)
the rubber handle became sticky as old synthetic rubber can do. I just wrapped the handle with some tape. It still works great.

[chriscowles]

Originally Posted by MevetS

The suggested method would be : https://asq.org/quality-resources/gage-repeatability

Thanks, but I don't think I'll be doing a GR&R study.

[chriscowles]

Originally Posted by KyDan

Consumer Reports recommends these 2 as their top choice for
both accuracy and reliability.
Accutire MS-4400B

and the

Accutire MS-4021B
both around $10 more or less.


FWIW I have a 4021B and after several years (like maybe 8 or so)
the rubber handle became sticky as old synthetic rubber can do. I just wrapped the handle with some tape. It still works great.

Thanks. I have a CR subscription but didn't think to look there.

[itat]

I use a Moroso analogue gauge as my trusted gauge but honestly I’ve never had it tested for accuracy. IMHO, a couple of psi either way you’re probably OK. If my Moroso dies I’ve added the Accurite to my Amazon.ca Wishlist but I’ve bought highly rated digital gauges off Amazon in the past that only lasted a few months or less so I’m very hesitant to try another one. The Accurite sells for CDN$40 on Amazon.ca.

[TitanMike]

Originally Posted by itat

I use a Moroso analogue gauge as my trusted gauge but honestly I’ve never had it tested for accuracy. IMHO, a couple of psi either way you’re probably OK. If my Moroso dies I’ve added the Accurite to my Amazon.ca Wishlist but I’ve bought highly rated digital gauges off Amazon in the past that only lasted a few months or less so I’m very hesitant to try another one. The Accurite sells for CDN$40 on Amazon.ca.

Interestingly, a variation of 10%, especially if low, can bring on tire problems

For a LR-C tire that can be 5 PSI. On a passenger car tire that can be only 3-4 PSI.

Having an accurate gauge can really head off tire problems.

I prefer digital gauges as the mechanical/analog gauges ( especially the pencil type) can easilly be subject to damage while in storage. Dial type gauges don't usually fare well if dropped. Even if the glass doesn't break the internal mechanism suffers with the clock-like gears used.

[MR.M]

I use the jaco digital air gauge . seems to match with the stock tpms in my truck . getting air gagues to all match is almost impossible . I doubt when i pump up to 80 psi and the tpms matches the gague that it is really 80 psi but will have to do . Even the shop that changes my tires all have gagues that differ by a couple pounds

[Bob K4TAX]

A man with 3 watches never knows the correct time and a man with 3 pressure gauges never knows the correct pressure.

A man with one watch always knows the time. A man with one air pressure gauge always knows the air pressure.

Get ONE gauge and stick with it. It will most likely be +/- 10% or so of the real pressure. Throw the other two away.

To wit.......I had the tires on my truck rotated recently. They checked the air pressure in the tires after doing so. However, they use a hose and gauge on one side and then a different hose and gauge on the other side. Guess what? I had 4 tires with 4 different air pressures.......according to the Auto Zone pressure gauge I use. I let some air out and put some in from my shop compressor. All is now happy and my truck's onboard tire pressure monitor shows 31 lbs on each of the 4 tires.

[ependydad]

I'd trust a digital gauge over an analog one any day of the week.

[rfifer]

I have a heavy-duty air pump that is typically off by 10 PSI or more, so I had been checking the pressure with a digital hand-held air gauge. I have since replaced the old air pump with a new one and now have agreement between the air pump and the digital hand-held gauge. As was mentioned above, 1 to 3 PSI difference probably will not matter. But when you start approaching 8-10 PSI difference, that can be a different story given the weight of the trailer and the observation that more often than not, the tires on a trailer are not of the highest quality.

[itat]

While I would tend to agree on the preference for a digital air pressure gauge, I haven’t found one yet that lasts longer than a few months before it stops working. Maybe they just needed a new battery and I had no idea how to change the battery? Anyway, my Moroso 89570 analog dial gauge always works (since I bought it in 2015) and seems to be consistent. When I use other gauges they show a slightly higher pressure than the Moroso reads. I refuse to replace a digital gauge once a year or more just to have a digital display so I’m sticking with the analog Moroso dial gauge for now. An equivalent Moroso digital pressure gauge (Moroso 89576) costs CDN$142 on Amazon.ca.

[jd4010]

I have air gauges galore around farm some used for tires with liquid ballast others for just air. Some digital some analog. My favorites are the digital for the air based tires like the RV and truck but for the final say, I use our PressurePro TPMS. At 110 psi, the digitals are about 2lbs (1.8%) different than the TPMS. So when shooting for 110 on the RV, I get the digital to read 108.

To me the TPMS is the most accurate. The truck has built in tire pressure sensors plus I use the PressurePro on the tires as well. Both the Ford TPMS and PressurePro match.

[jkoenig24]

At some Escapee RV events, they have a service that will check the accuracy of attendees' tire gauges. Years ago, there was NO charge to have your gauge(s) checked. I don't know if that's changed. A GOOD tire shop should have the ability to check the accuracy of tire gauges. As mentioned, as long as a gauge is at least close AND consistent, you should be OK. The IMPORTANT thing is to check tire pressure REGULARLY for PSI level and general condition of your tires. If the PSI of COLD tires stays the same morning, after morning, after morning; you're probably good to go.

[chriscowles]

Originally Posted by Bob K4TAX

... Get ONE gauge and stick with it. It will most likely be +/- 10% or so of the real pressure. Throw the other two away. ...

I don't have 3 separate independent gauges. I have one gauge for checking tire pressures occasionally, one TPMS for monitoring while driving and one Viair air pump which has a gauge on the inflation gun, so I know how much I'm putting in the tire.

Which two should I get rid of?

[n1acguy]

Milton is still in business. Reminds me that I need to order a new one. I have the same problem with the cheap Chinese junk. They all read differently.

[Cb25 Joe]

Milton S986 Service Gauge. $23 on Amazon and has great reviews.
I needed one that went to at least 80 psi for my Goodyear Endurance tires.
I’ve had mine for several years and it matches the psi from my tpms.
Made in the USA.

[n1acguy]

Originally Posted by ependydad

I'd trust a digital gauge over an analog one any day of the week.

The only thing that's dead nuts on a digital tire gauge is the display.
How well the sensor is integrated and designed may vary by quite a bit. Just like a digital scale.

[chriscowles]

Originally Posted by ependydad

I'd trust a digital gauge over an analog one any day of the week.

My concern is dead batteries. I'm likely to need it when they're dead and I won't have the specialty batteries it requires. I specifically ordered an analog dial gauge on my Viair pump for that reason. In a crisis on the side of the road, I don't care if it's a couple pounds off, but it drives me nuts when I'm prepping for a trip.

If digital is better, can I assume the TPMS is more accurate than the two analog dial gauges that differ, even from each other?

[AbdRahim]

Not uncommon. I have several and they differ by one or two pounds. I fill to what the tpms says, since that is what I watch, and get all of the tires to match there.