What I wonder, is how is one sure that a gauge, be it cheap, or a more expensive one, accurate? I once read that the digital ones are the most accurate. I have a digital, and a mechanical analog one, and a couple pencil gauges. I had more, but a I started checking them against one another, and threw out the ones that gave readings that varied more than 2 lbs from the others. Even so, the remaining ones don't all read exactly the same, but within 1 or 2 lbs, so I guess that is close enough.
I've purchased 3 different analog face guages, and a digital guage, and all 4 read a different PSI on the same tire at the same moment. Prior to that, I had 2 identical Slime brand analog guages that read different from one another.
Without anything else I could base the accuracy on, I set aside the one that read closest to what the TPMS on 3 different cars said (turned out to be the digital guage), and threw the other 3 guages in the trash.
The last pencil guage I used caused me to overfill a tire by 15 lbs before I realized that the slider was sticking on it's way out, so no more of those, thanks.
I'd be very interested if someone knows of a guage that is really accurate, and will still be accurate 3 months from now.
I like the pencil style tire psi gauge. The better ones are quite close in accuracy and it's also repeatability that I look for. Not one that's all over the place while trying to get an accurate reading.