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To: lml
Date: Fri, 09 Feb 2007 12:18:45 -0500
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From: "Bill&Sue" <5zq@cox.net>
References: <list-1826492@logan.com>
Subject: Re: [LML] Re: Air or nitrogen?
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Hi Kyrilian,

Nitrogen has several advantages over air in tires.  It's lack of moisture 
adds to the longevity of the rubber compounds. The lack of oxygen likewise 
helps preserve the rubber. Nitrogen expands and contracts with temperature 
less than air helping to keep pressures more constant.

The airlines use nitrogen in their tires for these reasons. Airliner tires 
are inflated to around 200 psi. Even a small airliner, say an MD80, has a 
max landing weight of 130,000 lbs and at that weight would touch down around 
130 knots. In general they're asking a bunch more out of their tires than we 
do.

For us in the Lancair world the advantages of nitrogen are simply not worth 
the trouble. Your tires will wear out WELL before any meaningful 
decomposition could take place. Since our tires are inflated to somewhere 
around 50 psi, a given % pressure change from temperature would be a much 
smaller psi change than airline or military tires.

My suggestion would be to stick with regular air. Use the money you'll save 
to by avgas.

Then again, you could fill them with helium and you'd need less lift from 
the wings! :-)

Bill Harrelson
N5ZQ 320 1,300 hrs
N6ZQ  IV under construction


>  Should tires be filled with air or nitrogen?  A few months ago the 
> benefits
> of nitrogen for use in oleo struts were discussed.  I  imagine nitrogen is
> better, but how critical is this in tires?
>    Cheers,
>   - Kyrilian