I'm a dinosaur, It would never occur to me to look at the sidewall (or anywhere else) to see what pressure I should ride. I choose pressure based on tire size, road ridden, tire grip, the bike it's on and how it's loaded. Jump on the bike and ride. Fine tune from there. Thumb squeeze when I like it for duplication, I usually never do know the actual pressure until I duplicate the thumb squeeze with my floor pump with gauge. (I rode sewups 20 years with nothing but frame pumps on all my bikes, no gauge at all. Sometimes I got to use a floor pump at races and actually knew the pressures but usually no.)
One thing I take real issue with is anyone telling me I should be using less than 5 psi lower in front than in back. That was what we all were taught back when we came from eggs (remember the dinosaurs). But there is a really good reason for so much pressure up front. There might just come a day when you have to slam on the brakes and do maneuvers to save your butt. At that moment, all your weight is on that front tire. Not 40-45% of your total. Not the 55-60% that the rear tire sees. No, that front tire is looking at 67% more weight than either tire sees normally. And at that moment, control is paramount. A blowout or rim failure disaster.
Ben