RE: Guess, mpg

From: Pindell, Timothy (TPindell@otterbein.edu)
Date: Fri Jul 30 2004 - 11:07:50 EDT


I wonder if it has anything to do with the >humidity< of the air used to
inflate the tires.

> -----Original Message-----
> From: james.zito@ps.ge.com [mailto:james.zito@ps.ge.com]
> Sent: Friday, July 30, 2004 8:16 AM
> To: dakota-truck@dakota-truck.net
> Subject: Re: DML: Guess, mpg
>
>
>
> > I was at Costco the other day...they had a sign up
> > about putting nitrogen instead of air into your tires.
> > I don't know if it was free or an "add on". Anyone
> > know the merits, if any, of nitrogen over regular old
> > generic air?
>
> My brother is a Tire Center Manager for Costco and he was
> telling me about this the other day. I thought it sounded
> weird at first, but it makes sense now that he explained it.
> Due to the physical properties of Nitrogen, it won't bleed
> out through the tire, thus keeping your tire pressure more
> constant, less refilling. It also won't fluctuate as much in
> the hot/cold like regular air does. Don't know if it's free
> or not, but I could check.
>
> - -Dave
>
> Ok guys, here is my take on it, generic air is 79% N2 21% O2
> and less than a % of other gasses (I know that this adds up
> to 101 but the 79 and 21 are also padded just a little). N2
> is a slightly smaller molecule than 02 (N has atomic # of 7
> and O has atomic # of 8 atomic weights are roughly double the
> numbers).
>
> Based on the basic composition of air I don't think there
> would be any real difference on the bleed out except for the
> <1% that is made of really lite gasses. Although the fact
> that N2 is smaller than O2 would lead me to believe that it
> would bleed out just a tiny bit faster than regular air.
>
> Now you do save about 2 grams per mole of N2 over O2 so I
> suppose you would end up with a tire that is maybe enough
> liter that you could detect it. (This is the reason that some
> racers fill their tires with He reduces the mass considerably.)
>
> Jim
> just chiming in to muddy the waters.......
>



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