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OT: Nitrogen filled tires

Discussion in 'Electronic Design' started by mpm, Sep 21, 2007.

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  1. mpm

    mpm Guest

    Things seem pretty slow in SED today, so let's talk about "Hot Air".
    (Like the kind in your tires.)

    Every so often I read something like this:
    http://fleetowner.com/news/topstory/fleet_nitrogren_beats_air/
    suggesting Nitrogen is better than air for improved mileage, lower
    tire wear, reduced Global Warming, etc....

    The trick is you fill your tires with Nitrogen instead of compressed
    air.

    Huh?! Air is 78% (or so) Nitrogen anyway.
    Is there anything to this, or is this a classic signal-to-noise
    problem...??
    Notice too that the article does not mention any service stations so
    equipped...

    -mpm
     
  2. Guest


    Quick! Start a nitrogen franchise, and make big bucks!

    Waste of cash.

    http://www.cartalk.com/content/columns/Archive/1997/September/05.html
    http://www.straightdope.com/columns/070216.html

    Michael
     
  3. I do it by filling the tyres with normal air, then putting a small
    amount of magnesium metal or benzene-1,2,3-triol into the tyre, this
    will absorb the oxygen. I get incredible millage, but the tyres keep
    wearing out quickly, mainly from the inside


    Martin
     
  4. Guest


    It would be useful if Drexan's cost per nitrogen fill-up were given -
    then, one could determine the break-even time, if any, for the whole
    fleet, using nitrogen fill-ups vs. the cost of the additional fuel
    consumed. Since this information is not given, though, I'm going by
    the $100 per fill-up quoted in the Car Talk article... and, clearly,
    there, it is not worth it for the individual user. $100 can buy at
    least two fill-ups for my Camry (though, probably not for an SUV...)

    Michael
     
  5. John Larkin

    John Larkin Guest

    You could fill a tire with a high-molecular-weight gas, like a freon
    or something, and it might leak less.

    I used to fill my bicycle tires with propane, for that reason and to
    avoid pumping. Of course, that has at least two tricky side effects.

    John
     
  6. mpm

    mpm Guest

    Unintended castration and... ???

    I'm glad to see Cecil didn't actually poo-poo the idea, but he's
    certainly skeptical.
    As for Click & Clack, (a lot of the time), they might be confusing N2
    with NOS.? :)

    If people are making $100 bucks a pop putting Nitrogen in tires,
    electrical engineering might not have been the best choice in
    retrospect.

    -mpm
     
  7. DJ Delorie

    DJ Delorie Guest

    Mine have nitrogen in them. I've got a lifetime free refill plan
    (part of the usual lifetime service plan, it was cheap), the tire
    station makes the N2 itself from air. In my case, the water and
    oxygen inside the tires led to some internal corrosion, and
    occasionally the tires would just deflate due to broken beads,
    especially in the winter. The tire station cleaned them up and put N2
    in, they say they've seen good results with it.

    Whenever my tires get low, I bring it in (no appointment, no charge)
    and they suck all the old N2 out and refill with fresh N2, and I drive
    away.

    They claim the tire pressure is less affected by the tire temperature,
    too, which may account for the 3% fuel savings in that article.
    Truckers spend a LOT of money on fuel, so tiny savings are a big deal.
     
  8. Guest

    Well the Montreal Metro runs on N2 inflated rubber tires.
    http://emdx.org/rail/metro/principeE.html
     
  9. John Larkin

    John Larkin Guest

    Going flat on very cold days.

    John
     
  10. John Larkin

    John Larkin Guest

    PV = nRT for any gas, right?

    John
     
  11. Guest

    If there was moisture trapped inside, tire temperatures have a wide
    enough range that you could get phase changes.

    G.
     
  12. DJ Delorie

    DJ Delorie Guest

    Except that "n" changes when you hit the dew point.

    At least, that's my guess. I just don't want the water and oxygen
    inside my tires any more. It sucks changing a tire in a snowstorm.
     
  13. Tim Williams

    Tim Williams Guest

    Any *ideal* gas. A Van der Waals gas comes closer:
    (P + a / V^2)*(V - b) = n*R*T

    Note that, for P >> (a / V^2), V^2 >> a and V >> b, or for a = 0, b = 0,
    this reduces to an ideal gas. Any gas looks ideal, if the volume is large
    enough.

    Tim
     
  14. Guest

  15. Damon Hill

    Damon Hill Guest

    Required on most aircraft for safety reasons: the tires can
    get hot enough under severe braking to ignite internally and
    explode.

    Actually, they can do so anyway, but via a relief valve.

    Not sure about the alleged benefits. Has anyone tried sulfur
    hexafluoride? (Despite the name, it's dead inert and has a high
    molecular weight.)

    --Damon
     
  16. Jim Thompson

    Jim Thompson Guest

    "suck out the _old_ N2..."

    Bwahahahahahaha!

    Must be Slowman's kid ;-)

    ...Jim Thompson
     
  17. Jim Yanik

    Jim Yanik Guest

    wrote in

    and about 20% reactive oxygen.
    A FIVE percent drop in tire pressure affects your mileage.
    Then why do high-end race cars run N2? They would not bother if it didn't
    matter.And they have close relationships with tire manufacturers,who ought
    know about such matters.

    N2 does not combine with the tire compound like the reactive O2 does.
     
  18. Jim Yanik

    Jim Yanik Guest

    "dead inert"? a *fluoride* compound? It even sounds toxic.
     
  19. Guy Macon

    Guy Macon Guest

    Next time, insist on Helium. Places that fill tires with
    Helium instead of Nitrogen always have lots of repeat
    customers, so it *must* be good! :p

    A related question: I am about to install new speakers in
    my convertible. Should I point them to the rear for better
    gas mileage, or point them up for better traction? :0
     
  20. Bob Myers

    Bob Myers Guest

    However, there is a very significant difference between
    the conditions under which a racing tire operates - for
    all of its hour or so (if that) of life - and those seen in
    passenger-car service. Do you think that MIGHT have
    something to do with the use of nitrogen in racing, such that
    those same reasons wouldn't apply at all in everyday use?

    Bob M.
     
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