Plus one for digital gauges. I used my floor pump’s attached gauge, as well as an old dial gauge for a long time, got to know what psi worked best for me, and figured I was in the ballpark.
A few years ago, I started wondering about the recommended pressures for various tubeless tires, mostly MTB stuff at the time, since I was still running tubes in my road tires. What always seemed odd to me was how much lower folks were claiming that they ran their tubeless tires, especially when tire size and rider weight was provided.
The numbers I was seeing were several psi lower than what I could get away with unless I was willing to suffer sidewall cut scenarios, which I originally did and which drove me away from tubeless for a long time.
But I did finally go tubeless on my MTB and didn’t regret it but was still using the old dial-type and sliding stick-type gauges. Well, I FINALLY bought a digital gauge, not an expensive one either, (*edit: I just read the BikeRadar Best tyre pressure gauges article linked by @CPT_A above, and mine looks identical and functions just like the LifeLine gauge in that article) and according to that gauge, my previously acceptable pressures were now showing as about 3-4 psi lower than what my other gauges said, i.e. 24psi now instead of previously about 28psi, for my 29x2.35" NobbyNics.
That lower number put me much more in line with what I often heard or read for safe pressures others could run on tires like mine. So I concluded that I had already been running pressure similar to what others of similar weight and tire-sizes seemed to run, but my gauges had been giving higher-than-actual readings.
Now, whether the digital is ACTUALLY more accurate, I can’t say, but what I CAN SAY is that I’ve converted to trusting that gauge more than any other I have, and I now know how to differently interpret the floor pump gauge readout and I compensate accordingly.
It’s my opinion that a difference of a couple psi may be minor in some scenarios, maybe most, but 5psi either way can be a significant difference in ride feel and traction, as well as some difference in rolling resistance, not to mention cost in terms of tire failures due to UNDER-inflation.
(Off topic here: I also used that digital gauge yesterday when I had to install a new pressure switch for my well pressure system, and in the process, checked the psi of the pressure tank pre-charge.
It was MUCH lower than it should have been, testing at 35psi, with a faulty pressure switch that was turning on at 42psi, and which SHOULD have been turning on at 50psi. That’s pretty far off from the minimum of 2psi to 5psi lower than than CUT-IN pressure that is recommended.
I was glad to correct the range for the switch, raising the new one to hold from 49-69psi for my desired pressure, and raised the pressure tank pre-charge to 44psi according to the digital gauge. So even if the digital IS a tiny bit low in its readings and the actual is maybe 3 higher than readings, I’m more confident that it leaves space for the 2psi differential that should be there to assure that the pump will actually trip ON before the pressure tank completely empties, resulting in zero water flow to the house till the pump turns on again.)
