Air pressure gauge



I have eight air pressure gauges, three dials and five pencils types. Some were free some I purchased. All seemed to work well. They are all in good shape. However the other day I was using one on my truck and I had to add lots of air to meet the truck tire pressure spec. I became curious so I got another gauge. There was a major difference is readings. So then I checked all eight gauges on the same tire and documented the readings they ranged from 50psi to 34psi. The average was 44.5 psi. Three units met the average, two dials, one pencil, which by the way one was purchase the pencil (USA), one was a gift from a Japanese motorcycle company (Taiwan) and one was just an old dial unit (Taiwan) I can?t recall how I got. The units that didn?t meet the average, some were free some were purchased. Besides wear and gas economy tire pressure is a very serious safety issue for motorcycles.

So my question is how can you tell you have a good tire pressure gauge?


Don’t assume the ‘average’ is correct. As for what to buy, I stay away from pencil types, and have read (somewhere) that the digital types tend to be pretty accurate.


Seconded on the digital gauges. And a lot is in how it’s applied, too. If you get it slightly off center you can pinch off the air delivery and end up with a low reading.


I googled ‘tire gauge accuracy test’ and found this extensive (and extended) discussion. Bottom line, the digitals were quite accurate, as long as the instructions were followed (some required a zeroing step).


Pencil type guages are “fragile” and may start giving accurate readings when new. After being used, and perhaps dropped they can suffer damage and give bad readings. If I get a “suspect” reading I check it with another guage or two if available. Then toss out the suspect guage if the reading wasn’t confirmed as accurate.


Having the same issue a while back I went and bought a decent dial gauge by Accu-gauge. I used that to test all of the other gauges I have around. Of the half dozen or so that I had most were clearly screwy. I ended up keeping 2 pencil gauges. One that always read the same as the dial gauge. The other always read 1-2 lbs. short. I store the dial gauge out of the way in my garage and just use it once in a while to re-check the two pencil gauges which each ride in one of our daily drivers.

Of course, I just have to assume that the dial gauge is right. After looking at that thread texases posted, I’m thinking I should go get one of the better digitals.


Each time you check tire pressure, you let a little air out, so no two readings will be the same.

Tire pressure is more important for motorcycles than cars. However, that is why motorcyclists are supposed to check their tire pressure at least once a week, while most car owners can check their tire pressure once a month. The quality of the gauge isn’t all that important. What is important is that you not neglect your tires.


Ah yes, one of my favorite topics.

The only real way is to get one of your gauges tested at a scientific instrument calibration service. This may cost you around $30 or $50. They can compare your gauge to their standard which in turn will have been compared to a national standard at NIST. The key words are “Calibration Traceable to NIST” and a dated certificate will be supplied.

You might be able to save a few dollars by asking for your gauge to be checked at a few critical points around where you will use it such as 30, 35 and 40 psi. You can use this gauge as your personal or even neighborhood standard but store this gauge in a safe place and use it only to check other gauges. Your standard gauge need not be adjusted to read perfectly as long as you know its error but this would not be acceptable for multiple users in a hurry to produce results.

Another way is to buy a new Bourden tube gauge that comes with a calibration certificate to use as standard.

Anything other than doing this is guessing. Fortunately tire pressure settings within a few psi of specified are not critical for motor vehicles which explains the situation as it is now: buy a good gauge for $15, never get it checked, hope for the best and believe for the rest of your life that it is accurate.

In the scientific and engineering worlds, pressure gauges, meters, calipers, voltmeters, micrometers, oscilloscopes and the like are typically checked once per year. Initial cost whether low or high means nothing as calibration checks are needed periodically due to accuracy drift due to age, storage conditions or abuse that is unintentional or otherwise. A brand new measuring device if requested can be supplied with a certificate to indicate initial calibration accuracy but this will expire in time.


I recently needed to replace some old gauges, so I did some Internet reading. It seems to be generally agreed that dial gauges are better than pencil gauges, but opinions differ on whether digital gauges are better than dial gauges. After looking at all of the reviews and comments, I ended up buying three Accu-Gage dial gauges. They all agree perfectly, so I’m hoping they’re accurate. They also feel like they’re solidly constructed, for what that’s worth.

One thing that I learned is that dial gauges are most accurate in the center of the range, so you want to buy the right range for your particular situation.