Tire Pressure Issue

[7rider]

Inner tubes are porous. They will slowly loose air. The higher the pressure in the tube - the quicker it goes down. Your tubes are a good example with 100 psi down to 80 psi. I pump my mountain tire up to 35 psi. I can check it a week later, and it will be at 32/33 psi.

This is why I always sell a floor pump with a road bike sale.

Interesting on the pump sale. I hope you instruct them on the importance of using it and how to use it. I know folks who have a pump, and never seem to use it! I guess they enjoy pinch flats??
I check my tires before every ride...I can't say I lose 20 pounds in a day, but I definitely need 2 or 3 pumps from the floor pump (more, of course, if I haven't been on the bike all week). I run my road tires b/t 105-110 psi.