Tank quanity is measured in Standard Cubic Feet (scf)
A standard cubic foot is a measure of quanity of gas, equal to a cubic foot of volume at 60 deg. F and 14.696 psi (1 atmosphere of pressure).
A scf is thus not a unit of volume but of quantity and cannot readily be converted to volume since the temperature or pressure may no longer be standard.
To correct for a non-standard temperature or pressure, when P (pressure in atmospheres) at a temperature T (in Kelvin; which is Celsius +273), multiply P by 273 and divide by T
or- Yes the quantity of Nitrogen (Standard Cubic Feet) inside the tire, does change as the pressure in the tire increases.
