Fundamentally, air, oxygen and nitrogen will all behave exactly the same, in terms of just how much pressure will change for each 10 degrees of temperature change. However, temperature alone is not the whole story. Ambient air contains moisture, which nitrogen does not. If moisture is there, it contributes to a greater change in pressure, simply because at lower temp, water condenses to become a liquid. A liquid form of water occupies very little volume and contributes only a negligible pressure to the tire. But at higher temp, water becomes a gas; water evaporates inside the tire as temperature rises. With ambient air, which contains about 20.9% oxygen, the oxygen permeates through the rubber of the tire, so some leaks out. With nitrogen, containing only a little residual oxygen, pressure changes due to oxygen loss are greatly reduced. So, on both counts, the race car guys are correct; nitrogen is more predictable - nitrogen is dry; it has no moisture to contribute extra pressure changes with temperature. And nitrogen permeates out much slower than oxygen, so pressure changes due to that leakage are almost eliminated, compared with ambient air.
The Paragraph above was taken from the link
Does anyone else see 'BS' written all over this paragraph?
As the link says all gases expand at the same rate so you will see the same increase in Pressure with a measured increase in temp. for air as Ni. (or for any mix of gases for that matter).
“But at higher temp, water becomes a gas; water evaporates inside the tire as temperature rises.”
If water becomes a gas then it behaves exactly as the other gases including Ni, they say that in the first sentence. With regards to moisture content in the tire can someone explain to me how water vapor that expands less than or the same as a gas can affect the total volume/pressure of a tire when it occupies less than 1% of the total gas in the tire. This reasoning has been mentioned a few times in this thread. If you believe this and want a gas that is dry and behaves exactly like Ni fill your tires up with the same air you spray paint with. No moisture, no problems.
“And nitrogen permeates out much slower than oxygen, so pressure changes due to that leakage are almost eliminated, compared with ambient air.”
How is the leakage of a few molecules of air going to affect a tire in a few hours of a race? (Even if this is true your talking about such a small amount of time difference it is probably incalculable).
Keep in mind this web site is put there by the people selling Ni. I think the Ni theory for road vehicles should be on the same shelf as the rest of the snake oil products that the auto industry seems to be saturated with.
I have yet to read a decent explanation as to why it is advantageous to use Ni in car tires.