Looking for the best tire pressure gauge

When I was a kid in the 80's I remember my dad read an article that said the cheap, pencil-style air gauges were the most reliable. 
 

it has stuck with me and I kind of default to them.  Well, I checked my pressures yesterday at the track against two of them, one accu-gauge dial gauge and a $20 Amazon digital. 
 

Not sure if I was surprised or not, but the hammer store pencil style was 5lbs higher than the other pencil style of unknown origins, and the accu-gauge dial was also reading 3-5 lbs higher.   The harbor freight one would also read differently by 3-4 lbs every time you put it on. 
 

I would like to know what the best gauge is that would be under/around $100. 
 

it's a lot for a gauge but I realized that apparently my pressures have been 5lbs off of what I thought they were more than one track day. 

I've always thought that the best tire pressure gauge is "the same one you've been using." In the end, the exact pressure you run numerically doesn't matter, it only matters that once you find the ideal pressure, whatever that is, you can repeat it. 

So basically, just one that consistently reads the same, whether it's right or wrong in terms of actual PSI. 

I think I have a longacre one that I consider to be consistently accurate, so that's the one I generally use for things. 

Yes, good point.  But how do you know if it has changed? That's why I want a good one known to be consistent and last.

I also want to know that my initial settings are close and not apparently 5 or more lbs off!

I suppose the real answer is to get hot tire temps straight from the track but that's not always (or rarely, in my case) feasible. 
 

I have seen longacre gauges before and they do seem like they'd be good

I'd always assumed the nifty dial type were best, but i read a while back that some of the best are good pencil types. Lee Parks (of motorcycle training fame) sells one. At $7.95 you can put one in each vehicle and foist them on friends who need reminding about tires.

https://leeparksdesign.com/accurate-tire-gauge/

i confess i have not performed my own testing.

I keep two gauges in my kit. One moroso one longacre. I know that at the beginning of the season they measured close to each other. If I ever question it I grab the other gauge and see if I get the same result. I like the longacre gauge a bit better. 

I really like the two Longacres I have, but they're not exactly "chuck 'em in the trunk" cheap so they only get to leave the garage if I go to the track. Other than that, I'd say the one you keep in the car - you can always "calibrate" that against the good one at home, and I find that most of the time I needed one on the road, it wasn't because the tire pressure was a couple of PSI off...

My longacre dial gauge has been my go to for accuracy.  I misplaced it recently, and if it doesn't turn up soon, I'm buying another.

No matter what gauge you wind up using, get one that reads to slightly above the expected range you need. This does two things: it allows you to be as precise as you want to be with setting pressures, AND it gets you to the highest resolution for the gauge mechanicals.

I also have a Longacre that I use for track/autocross/maintenance stuff. It has a range of 0 to 60psi. That covers all the vehicles I typically work on. If I were chasing an autocross specific gauge, I would probably try to limit the top end of the range to 30-45psi.

For calibration/cross-checking, I rely on the battery powered airpump with it's onboard pressure gauge and cross-check it to my Longacre. Also have a small dial type that I carry for road trips. One more thing, digital is great if you are chasing a 0.1 psi increment and they can be calibrated, but mechanical never needs batteries.

In theory either a mechanical dial gauge or a digital one should be the most accurate (Edit: meaning remaining accurate over time, maybe I should say reliable). The pencil gauge uses a combination of spring pressure, inertia and friction to show the tire pressure and the wrong level of friction in the device (too much or too little!) or metal fatigue in the spring can both throw it off. From my experience their accuracy isn't the best, but it's kind of surprising that it isn't worse.

A mechanical dial gauge is an entirely flexure-based device, air pressure inflates a flexible metal coil like a balloon and the gauge shows the deflection translated through a mechanical linkage. The only thing that will mess it up is metal fatigue or physical damage.

A digital gauge uses a flexure-based MEMS sensor so essentially works on the same principle as the mechanical dial gauge, just a very tiny version with electrical measurement.

I have a couple of these and they've remained accurate, once saw a video where Rimac's engineers were using the same model:

https://www.sears.com/victor-automotive-00881-8-pro-dial-tire-gauge/p-SPM11935580616

Your favorite magazine did an article many years ago (apparently prehistoric) that concluded the most basic digital gauge performed equal or better than high-end mechanical units.

In a competition environment, a bleed-down button is essential.  

I routinely QC my various gauges against one another - luckily they are all consistently within a small margin of error.

Most mechanical gauges should be read at a halfway point on the dial, similar to the need higher than what you're checking idea.

I have a moroso that reads to 45psi max. It's a steaming pile of E36 M3. If I'm deflating, I double bump the air release to make sure the pressure is the real pressure. Many times it is not the same reading. I'm going to get something else this winter that hopefully reads accurately.

I just wish the oe tpms read to the tenth on the display vs whole numbers.

bludroptop said:

Your favorite magazine did an article many years ago (apparently prehistoric) that concluded the most basic digital gauge performed equal or better than high-end mechanical units.

Yeah, it's much easier to keep an electronic load cell in calibration than it is the spring in a mechanical gauge.

https://www.longacreracing.com/products.aspx?itemid=1715&prodid=7354

Anyone have any experience with hammer store digital gauges?

https://www.amazon.ca/Astro-Pneumatic-3018-Digital-Inflator/dp/B002PUTC0M?psc=1&ref_=pd_bap_m_hero_1_ec_sf

I have several of these at the shop. One, at least 5 years old.  All read the same.

Note, $Cdn in the link.

In reply to drock25too :

I have an HF digital.  I haven't checked actual accuracy, but it reads the same as my Barjan truck stop mechanical within about 1 psi.

So the question is how accurate are the numbers on the dashboard?  My Silverado gives me exact number for each tire.  

In reply to Curtis73 (Forum Supporter) :

Thanks 

In reply to SoonToBeDatsun240ZGuy :

My Canyon is sensitive enough to pick up the pressure increase on the sunny side of the truck.

Well above the price range asked for here, but the best I know of by far is the Unipro Unitire. This comes from the karting world, so tenths of a psi make a difference, and the super low volume of a 5" tire makes any air line introduce uncertainty when checking. 

Start with this.

Place it in a small box, connect one or two nine volt batteries and a hose, BAM, accurate gauge with set points that change color.

I have two now, with SMC brand switches.

I just had the same problem. I found all my analog gauges did not work anymore and were inaccurate by at least 15-20 psi. Not sure what happened because they were name brand ones but my guess is being left in a hot Florida garage for years did them in. 
 

I figured I'd just try something digital from Amazon to start with. So I found this for $6 last week. It works well and came with a "certified" calibration card. 
 

ETENWOLF Digital Tire Pressure Gauge 3-200 PSI, Industrial Tire Gauge Calibrated to ANSI B40.7 Grade 2A(±0.5%), Replaceable AAA Batteries with Presta Valve Adaptor (Vivid Orange) https://a.co/d/iDwmUAo

based on my use so far seems like a good one

This is the one I got from HF.  Claims +/- 1%, so at 50 psi, that's 1/2 psi possible difference.

The TPMS systems in new GM vehicles has been great for me.  Other marquees not so impressive.  This seems like it should be perfect in any modern vehicle.  

If it doesn't have a function to zero the gauge for ambient temperature, it isn't that accurate.  IMO pencil-style mechanical gauges can be wildly inaccurate.

It really comes down to your needs in the end.  For track days, I think parts store digital gauges work for many.  The Longacre dial-type gauges are fine if you want to spend more money, but they can only get you to within 1/2 PSI or so.

The Intercomp digital gauge is the king IMO.  It's stupid expensive.  I race in a very competitive and rigid spec class, and accuracy to within 1/10th of a PSI is important to me.  I'm glad I own the Intercomp; it's a lifetime investment if you take the track hobby seriously.  If you really want the best, there it is.  Buy once, cry once.

Precision = how many digits you can read. This is difference between 35psi and 35.0psi

Accuracy = how close the measurement is to real life. Your digital gauge might say 35.0000psi, but it might still be a whole psi off. More precision than accuracy can give a false sense of accuracy. The cheap manufacturers knows this and do it on purpose. 

For example, this gauge has 1/10th psi *precision* but 2psi *accuracy*:

https://www.amazon.com/ETENWOLF-Industrial-Calibrated-Replaceable-Batteries/dp/B0BY2GD9VC/ref=sr_1_5?crid=EMY61PNOY2SN&keywords=tire%2Bpressure%2Bgauge%2Bdigital&qid=1695838891&sprefix=tire%2Bpressure%2Bgauge%2Bdigital%2Caps%2C82&sr=8-5&th=1

You need both. A perfectly *accurate* 2" dial gauge that reads up to 200psi will not be *precise* because you just can't see the difference in a couple of psi (depending on your eyesight, it could be even worse). If I know my highest pressure I'll set to is 30psi, I want a gauge that goes no more than 40psi. The wasted real estate on the gauge just hurts your precision. 

I find the stick gauges to be awful on both fronts. Measure the same tire three times, and I'll get three different pressures by several psi, and it is hard to determine <1psi. I trust my eyeballs looking at the sidewall bulge on a familiar tire more than I trust my own experience with stick gauges.