Nitrogen in Tyre
If you Google about filling nitrogen in car tyre you will get lot of good articles explaining the pro of nitrogen gas. I am not gonna explain good or bad of nitrogen, but intern my question is are we filling nitrogen 100%?
If you take your vehicle to petrol pump for filling nitrogen what they do is deflate your tyre fully then inflate with N2. So do you think your tyre has only N2 inside? (that too 100%?)
My answer is no.
if your cars tyre pressure is 30 psi (~2 atm) and when u deflate air pressure inside the tyre, it will reduce till it is same as atmospheric pressure (1 atm). That is deflating of tyre stops when pressure inside tyre reaches atmosperic pressure thats 1 atm (~15 psi). Now you are inflating tyre with N2. So you are mixing N2 with the residual air which is at 15 psi, till it becomes 30 psi which is the correct tyre pressure for your car.
So now inside tyre you have nitrogen as well as air(78% N2 + 21% O2). So inside your tyre it is not 100% N2....
Comments on this Post
Eventually O2 will diffuse through the polymer made of tyre and after 20-25 refilling of N2 you will have 100% N2 in tyre (Appx.)
Though i agree with you that its not exactly 100% N2, it is very close to that.The percentage of O2 in the inflated tire will depend on its volume as well as pressure.While defalting,the volume of tire reduces due to weight of the vehicle. Also since air is 78 % N2, most of the remaining air will be N2.