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Nitrogen in Tires

Discussion in 'Gen 3 Prius Fuel Economy' started by john burns, Oct 22, 2009.

  1. tumbleweed

    tumbleweed Senior Member

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    But I think you might need rims made from nickel and I'm not sure what you could make the tires out of. UF6 corrodes just about everything doesn't it? But I do have a calcium chloride solution for weight in the rear tires of my old tractor, of course it only has a top speed of 15 MPH.
     
  2. richard schumacher

    richard schumacher shortbus driver

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    If O2 did diffuse through tires faster than N2, after a few refills with plain old compressed air the tire would contain mostly dry N2 anyway. It's a complete waste of money to pay for a nitrogen fill. Just check your tires more frequently and you'll get more benefit.
     
  3. fuzzy1

    fuzzy1 Senior Member

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    What would make it dry?
     
  4. qbee42

    qbee42 My other car is a boat

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    No, that is just plain silly. The diffusion rate of nitrogen is pretty much the same as air. Air is almost all nitrogen and oxygen, which both have about the same rate of diffusion. The small amount of other gases are too small to have much influence, but if they did, they would diffuse out and we would automatically have "nitronized" tires in short order.

    It amazes me that tire stores can get away with outright lying.

    No, not correct. Oxygen molecules are slightly larger than nitrogen molecules. As you might expect, because of this the diffusion rate of oxygen is slightly lower than that of nitrogen. Even so, it's a trifling difference.

    Tom
     
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  5. Gen 3 for me

    Gen 3 for me Member

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    My dealer adds nitrogen for free before delivery. I do not want nitrogen because I am concerned about the slight possibility of the tire bead changing position on the wheel rim when the dealer deflates to get the air out.

    At the auto assy plant I worked at we used an expensive machine to load the tire wheel assembly to seat the tire bead properly after mounting was finished. This was to get a more accurate balance on the assembly. I do not know whether or not Toyota uses this technology but I would think they do. Otherwise the nitrogen won't hurt and it is no substitute for regular tire pressure checks.

    I like the idea that when I do high speed driving that air expands more than nitrogen causing more pressure increase than nitrogen would. So I prefer air over nitrogen irregardless of cost.
     
  6. qbee42

    qbee42 My other car is a boat

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    This is simply not true. Nitrogen behaves like any other ideal gas. The expansion rate of nitrogen and air are identical for all normal temperatures and pressures.

    Tom
     
  7. dogfriend

    dogfriend Human - Animal Hybrid

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    What about Hydrogen? I want to make my tires lighter. I think I will use Hydrogen. :madgrin:
     
  8. carz89

    carz89 I study nuclear science...

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    We agree to disagree. All of the sources on the internet I found claim that Oxygen molecules are slightly smaller than nitrogen molecules. Thus the diffusion or permeation of oxygen is actually higher than that of nitrogen. Rather than quote all of the sources, just look up the covalent radii of each molecule in wikipedia, which is not perfect but generally accurate in these types of articles. If they are all incorrect, please feel free to correct the wikipedia articles yourself.

    [ame="http://en.wikipedia.org/wiki/Oxygen"]Oxygen - Wikipedia, the free encyclopedia[/ame]

    [ame="http://en.wikipedia.org/wiki/Nitrogen"]Nitrogen - Wikipedia, the free encyclopedia[/ame]

    The trifling difference in rate of pressure loss is mostly due to the fact that the "air tire" starts out with 80% nitrogen, so that it really isn't much different than 100% nitrogen.

    If you compared a 100% oxygen-filled tire vs. a 100% nitrogen-filled tire, you would see a noticeable difference in the rate of depressurization.
     
  9. GreenWithEnvy

    GreenWithEnvy New Member

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    You guys (and maybe gals I didn't really check) are just FREAKS. I mean that in the best way, honestly. :)
     
  10. dogfriend

    dogfriend Human - Animal Hybrid

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    Wouldn't 100% Nitrogen actually diffuse through the tire more quickly?

    Fick's law of diffusion - Wikipedia, the free encyclopedia

    If you have 100% Nitrogen inside the tire and 79% Nitrogen (Air) outside the tire, then you have a concentration gradient from higher Nitrogen concentration inside the tire and lower concentration outside tire.

    If you have 79% Nitrogen inside the tire and 79% Nitrogen outside the tire, then you do not have a concentration gradient.

    Think about that for a minute. :madgrin:
     
  11. garygid

    garygid Senior Member - Blizzard Pearl

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    The gas inside the tire is under substantial extra pressure, so the equal 79% concentration is not significant.

    Dry air (%79 nitrogen anyway) or dry 99% nitrogen should not make any noticable difference.

    However, the sloppy wet "air" (and actual liquid water) that comes out of the air hoses
    at many places ... is not even close to "dry".
    Try just "spraying" before you put it into your tire, to see what comes out.
     
  12. carz89

    carz89 I study nuclear science...

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    Huh? Didn't you forget something pretty darn important -- pressure difference? or more exactly, the differences in partial pressures between the inside of the tire and the outside.
     
  13. dogfriend

    dogfriend Human - Animal Hybrid

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    Is that important? :madgrin:
     
  14. tigerpilot

    tigerpilot Member

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    Here's my take on the silly Nitrogen subject.
    79% nitrogen in regular "air". That leaves 21% other stuff that is going to leak out of the tires. We then add regular air that has 79% nitrogen. 79% of 21% adds roughly 16% more Nitrogen to the original 79%. Now were up to about 95% nitrogen. After topping off the tires a few times were almost at 100% nitrogen automatically.
    Regards,
     
  15. esoniat

    esoniat Junior Member

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    How do you maintian tire pressure, what is the carbon foot print of nitrogen.

    Seems to me if tire pressure is important checking and filling will be of primary importance and filling with nitrogen will likely result in less frequent filling.

    Also filling with nitrogen requires a large carbon footprint for the creation, transportation and storage and if you have to drive to a special location to get it that too increases the foot print.

    I suspect a careful analysis will show this is not a good idea for anybody but the people selling nitrogen.
     
  16. qbee42

    qbee42 My other car is a boat

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    Here is the math from an earlier thread:

    We have been over this a lot of times. Here is a link to one of our better threads on the topic:

    http://priuschat.com/forums/gen-ii-prius-fuel-economy/34481-nitrogen-in-prius-tires-2.html

    Tom
     
  17. wvgasguy

    wvgasguy New Member

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    Even if you decide to fill with nitrogen and you live in cold climates, your pressure will drop as it gets colder and you'll have the aggrivation of going back and having more nitrogen added. A hand (bicycle) pump in your garage can keep the tire pressures exactly where you want them with little effort
     
  18. carz89

    carz89 I study nuclear science...

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    Yes -- "approximately", but in the case with N2 and O2, it is an anomaly confounding many when they first stumble upon it. Hence the relationship is not a true "law" able to be proven no matter what elements you plug in. Experimentation results done by scientists in laboratories have show that O2 permeates through rubber compounds faster than N2.

    So yes, there is some validity to the science supporting filling your tires with Nitrogen, but I think it's pretty fruitless. Just keep your "air" tires up to pressure!
     
  19. qbee42

    qbee42 My other car is a boat

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    Some of these molecules are tricky little beasts and don't behave as nicely as we would like. Take osmium and iridium for example. If you look at the numbers, iridium should be the densest natural element, but a quirk in the atomic structure of osmium makes it a tiny bit denser. Likewise it seems with the sizes of O2 and N2.

    Either way, as you point out, it doesn't make a lick of difference. Neither permeates well through rubber tires. Most of the nonsense around tires and nitrogen comes from the legitimate reasons that nitrogen is used in race car tires and airplane tires. Add to that the ability of unscrupulous vendors to make a buck from "nitronizing" tires and there you have it. Most of the "nitronizing" tire shops don't use pure dry nitrogen, and they still use water based lubricants when mounting the tires. It's pure snake oil.

    Tom
     
  20. dogfriend

    dogfriend Human - Animal Hybrid

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    Snake oil is the mystery ingredient that helps improve mpg. :madgrin: