Nitrogen Filled Tires

[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.

[Malt]

I agree with everything you've said in principal with a few small caveats.

Yes, Nitrogen is inert and non-flammable. Air is non-flammable as well. What normal tire fills have is oxygen which is an oxidizer. That's sort of a silly reason to condone nitrogen fills though because compressed air is exactly the same makeup as atmospheric air, just under pressure.

BUT WAIT!... tires are under-pressure which means you get lots of oxygen if a tires blows, which fuels the fire right?! Not exactly. Not sure if any of you have much experience with vehicle fires and tires exploding due to flame impingement but the main concern there is the explosive force of the rapidly expanding gas, not the sudden on rush of normal air providing an oxidizing agent and nitrogen filled tires will have exactly the same effect as a normal air filled tire in that regard. I'm quite sure that I've dealt with hundreds (if not thousands) more exploding tires due to fire than 99.9% of the forum goers here.

As for filling tires while at the track...



Weighs less, takes up almost no room, free to use, no refill cost, no electricity requirements, not limited by hose length from the trailer, etc...

Far superior to electric compressors or carrying around gas cylinders IMO.

[Hoosier Daddy]

Race teams use nitrogen. Not because it's expensive.

But Jeez, don't put it in your street car. Buy flowers for the wife instead.

[BRZZZZZZZZZZ]

Unless your driving a race car or flying a plane, don't bother.

All in my opinion.

[Decimus]

its free @ my costco and i can easily tell them to top off my tires. If it takes me the same amount of time at a gas station, i'll rather get it done with Nitrogen.

[rice_classic]

Originally Posted by Malt

As for filling tires while at the track...



Far superior to electric compressors or carrying around gas cylinders IMO.

You have a pretty good sense of humor. Heck, speaking of simplicity, let's just inflate the tire by blowing in the valve stem with our mouths!

[PunX]

We'll, i don't mind opposition, as a reply to MALT and rice_classic, i do agree there are no significant benefits of nitrogen over dry air. But not every country and gas station have air dry system in their compressors, actually i would believe i haven't seen anyone using such in Estonia. Checking the weather channel i see relative humidity of 90%, so i don't want to fill tires with that air right now, considering the pressure and density rise in tire as it's compressed, therefore can hold less humidity and condense water starts to form.
But as for testing, maybe autoX is not the best Technic to test such thing, i would propose drifting to be much more adequate Motorsport because this is where tires get some heat, i myself, have measured measly 180 degrees C from 10-15min practice run. Sadly i don't have have proper weather to do tests myself(all icy and slippery - less heat buildup).
About someone running 4 years with same tires, quite common as not all people in a world drive 80k in a year because they live in much smaller country and don't have long distance travel to work daily, to get for an example, the tires this car ships with should last approx 65'000 km(yes i know, on a prius maybe), but still, now if you are some grandfather visiting his son every week and drive 50km for that. Some countries even see snow and have separate tires with rims for winter, again your summer tires should last forever - considering not drifting daily. So please, let's keep our minds and heart open toward fellow FRS/GT86/BRZ owners, we are all good, smart, all-knowing and beautiful.