Even if Oxigen diffuses trough the rubber 5 times as much as Nitrogen,the pressure loss is in the beginning only less then 2 times as much.
The longer it lasts the more the partial pressure of oxigen comes closer to that of the outside air, and the advantage is less.
And , What I read is that oxigen only diffuses about 3 times as fast as Nitrogen, so difference is less already in the beginning.
The reason why they began with Nitrogen filling is that its was easyer on the road , better then a portable compressor.
Nitrogen is the cheapest gas that is delivered in cylinders.
Its a wasteproduct of the Amoniak- production, wich on its turn is used for artifical furtiliser.
if you manage to fill the tire with 100% Nitrogen , the partial pressure of Oxigen is zero bar/psi or whatever, the outside partial pressure of oxigen is constant 21% of 1 barr/ 14.7 psi.
so then the oxigen difuses into the tire , against the higher total pressure in the tire.
Most wont beleve this , but search for the Law of Dalton for that.
Says about that every gas behaves , for instance for diffusion, as if it was the only gass in the space.
So in the beginning after filling to 100% Nitrogen, wich is not possible, the loss of Nitrogen is a bit compensated by the oxigen goin into the tire.
