[rice_classic]

I did an experiment with Nitrogen and race tires for a college class a couple years back. I have a lot of data that proves and disproves a lot of BS about Nitrogen filled tires. I figured I would pick a few quotes to reply to and then share a little.

Originally Posted by stugray

If you use DRY AIR, there is no difference.
AIR is 80% Nitrogen AND ~20% Oxygen.
Nitrogen will experience EXACTLY the same change in pressure with temp as a cylinder filled with 80% nitrogen & 20% oxygen.
SCIENCE Bitches!

Pretty much this, but let's be specific. First, the whole point of using "pure nitrogen" is that it is two things: A large(er) molecule and a dry molecule (not part of H20). The very very very very very tiny difference between pure nitrogen and "regular air" is that the other gasses that make up regular air smaller molecules and they are molecules that naturally bond/attract/create moisture.

So why do we want dry air or pure nitrogen? That gets answered below.

Originally Posted by BRZ21

Dry air? Thats just as complicated to find...

You're right with your idea but in the real world "air" in your tires is whatever "air" your compressor pumps in... not dry.

I'm not wrong.

Been to Phoenix in August? Dry "air" is pretty easy to find. But all joking aside, even if you could scrub all moisture from the air OR you're using a tank of pure nitrogen it's all sort of irrelevant. Explained below.

Originally Posted by PunX

Now the big difference comes into play in moist and/or hot climate, as condensation water accumulates in compression tanks, it does so in your tires as well.

This right here. But the claims below are proven wrong in testing or should be further explained (RED):

Originally Posted by PunX

gains from nitrogen Should more accurately be described as "gains from a moisture free inflation gasses"
*even and very fast warm up for tires Even warmup is not because of nitrogen but because of the lack of moisture. That's an important distinction. We could fill our tires with pure Argon or Helium and achieve the same effect. The rate of warming is pretty much irrelevant to the gasses inside the tire but instead a product of friction across the tire compound.
*even wear What gas is inside of your tire is irrelevant to tire wear, tire wear is based on inflation pressure and alignment. I suppose if you're a long haul trucker and a pure-nitrogen tire maintains tire pressure 1-2 psi better than regular air, that could be a valuable difference in relation to tire wear on very long trips with heavy loads.
*more stable pressure through out very big ambient temp changes(example from +30C to -20C) Once again, independent testing has shown this to be insanely difficult to reproduce due to the reality that controlling the gaseous environment inside a pneumatic tire is insanely difficult, 100% nitrogen or not. Also, Nitrogen expands and contracts at roughly the same rate as Oxygen/Argon/CO2 so any benefit of running pure Nitrogren vs say, pure Argon or pure CO2 would be almost impossible to measure for the average joe with a tire pressure gauge and a clipboard.
*and debatable but possible, scientist say that because of Nitrogen molecule being bigger, it doesn't escape the tire from microscopical holes in rubber form so fast than Oxygen does. This is the most accurate statement here and is reproducible in a lab albeit over a very long period of time. A nitrogen filled tire will deflate itself over time more slowly than one filled with regular air. But once again, conducting a proper exchange of gasses occurs is difficult especially on any wheel with only 1 valve stem. Also we change our tires and pressures enough that it renders this advantage rather moot.

Originally Posted by Malt

Nitrogen fill is snake oil that tire shops use to try and up-sell you to increase profits.

The science is sound Malt, it's the practicality that isn't.

So I did testing with multiple 100% pure nitrogen tanks, 3 sets of race tires, multiple race weekends, tires that were dry mounted with dual valve stems for proper purging and ones that were mounted normally and I took every measure to ensure no moisture and no "regular air" was inside my race tires. I did comparison testing, session after session on multiple tracks/multiple weekends and back to back with tires that used regular air, lube-mounted etc.

NO DIFFERENCE, in fact sometimes the predictability in pressures was worse with the Nitrogen tires. But why? The answer is controlling the environment is practically impossible. Even with dry mounting tires, even with dual valve stems and lots of purging, it's insanely difficult to ensure not one molecule of moisture is inside that carcass and even if after all of that Nitrogen still expands/contracts with temperature pretty much just the same as regular, low-moisture, air. I'm sure that NASCAR and F1 teams are better at controlling what's in their tires and I'm sure they have different results but I also know, because Matchette explained it once that it's also a function of safety because Nitrogen is inert and not flammable.

I've scoured data from other racers/teams that have done the same testing, taken the same data and experienced the same results.

2 questions remain:

Question 1: So why do lots of racers have Nitrogen tanks in their trailers?

Answer: convenience. That's it. They are cheap to fill, and you can fill LOTS of race tires on 1 tank-full (like a 100 or so!). No pumps, no compressors. They are used because they 'simplify the weekend' and that's a very important function of racing; simplification.

Question 2: Is there ANY benefit putting nitrogen in my tires, especially if I'm not racing and don't care about the convenience of an air tank?

Answer1: Without moisture you greatly reduce corrosive properties that may exist to damage the inside of the wheel or the wheel rim, but this is not common enough to be much of a concern for most drivers.

Answer2: If you somehow are able to take the necessary steps to ensure no moisture and only 100% nitrogen are inside your tire then you may see a benefit on your daily driver where your tires won't deflate as quickly. However, due to how often we change tires, set pressures etc, the time frame to realize any benefits from Nitrogen's "large molecule" advantage will most likely not be realized. And when Malt says "Snake oil" that's why. The juice isn't worth the squeeze.

Answer 3: Long haul truckers who drive to lots of time zones and elevation changes and industrial machines. In this case they would use expensive machines to purge, measure and eliminate moisture from a tire while replacing the gasses.

Finally: I will be adding a Nitrogen tank to my enclosed trailer for the race track because I, too, like the added convenience.