and of course not all tubes hold pressure for the same length of time. Some tubes might hold 80psi for a week and some might go down to 65psi in a couple of days. I got used to thumping the tire for a particular tone after pumping it up with the floor pump to a particular psi. After a few months doing this you get familiar with the sound the tire makes and it becomes second nature to hit the front and back tire before riding as a rough check.