Nitrogen in tires

[Peter Rossato <rossato@xxxxxxxxxxxxx>]

Oh, despite my engineering degree I've gotten in trouble before trying
to play scientist on this digest, but I can't resist.

I missed most of the prior thread, but I do recall reading that nitrogen
expands very little compared to pressurized ambient air for the same
change in temperature, which is why professional race teams
(particularly open wheel cars such as F-1 or CART) use it exclusively.
That way they know the pressure in cold tires will not change much when
they are at max temperature. Where a few thousandths of an inch means a
radical change in handling the more variability you can take out of the
equation, the better.

Michael Kohlbrenner asks if it is because nitrogen is dry, and the
answer is yes.  Pure nitrogen has no entrapped water vapor unlike
ambient air.  I suppose you could use any gaseous element in its pure
form, but nitrogen being the most abundant element on earth (78% of air
is Nitrogen) it is the cheapest commercial gas available.

Next week, why NASCAR uses Nitrous Oxide to pressurize their roll bars
;-)

Peter Rossato
'94 325is "VDERZEN"

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