you could buy a good gauge and use it to calibrate your floor pump, mark a line on your floor gauge where, say, 100 psi is,

the human hand is a remarkable instrument, ever do autobody work? you know those tack cloths they use for removing fine particles of sanding dust before painting? well, a hand works better. use a tack clot and then rub your hand over the fender, you can feel every microscopic piece of dust on there, and the hand will pick it right up.

same with tire pressure. just feel the tires and not the pressure, after a while you will have calibrated hands.
this is handy when adjusting pressure for rain, or really cold days when the pressure will start to drop as soon as you leave the house. unless you pump tires in a freezing garage, which ani't a bad idea if you want the pressure to stay the same out on the road.

use to drop air pressure on the MTB at the top of a hill before descending and pump it up at the bottom, no gauge on the Silca so you used hand pressure.


when you flick your finger against the tire it will make a certain note, sewups made the loudest pop .you can use a Snark guitar tuner , i usually run an "F" in the front and a "F" sharp in the rear. (don't say G flat, bad karma)
unless you get a flat. then say, Gee, flat.