Yes you can, but it's fairly hard because air is a mixed gas. Each of the
gases has a different coefficient, so even though the pressure,
temperature and volume are calculable with Bernoulli's formula the change
is non-linear. You can fill your tires with Nitrogen instead of air and
enjoy both a smaller variation in pressure with temperature and an easier
calculation
-----Original Message-----
From: Wes Dayton [mailto:oilyrag@hsrca.org.au]
Sent: Monday, July 22, 2002 1:40 AM
To: Friends of Triumph
Subject: Tyre Pressure/Temperature
I hope my high school physics teacher isn't part of this group. Come to
think of it, he'd likely be about 150 years old by now, so it's not
likely!
My question - is there a simple formula for calculating tyre pressure
differentials based on the air temperature? For the moment, let's forget
the complications involved in tyres heating up during a race (that will be
part two of this line of questions).
For now I'm just interested in the basic question "If my tyres are just
sitting there, and the ambient temperature drops ten degrees (assuming
that it changes slow enough so the temperature inside the tyre drops the
same amount), how much will the tyre pressure drop"?
If the formula requires me to figure out the volume inside the tyres, then
it's probably getting all too hard. Or is it easy?
Maybe I should ask this another way? Has anyone else out there spent
Saturday getting their pre-race tyre pressures just right. Then you arrive
at the track on Sunday morning (after a nice crisp night) and found they
are four pounds lower and you say to yourself "do I have a leak, or are
things as they left them or what"?
Get my drift? And if I'm missing something very obvious, just be gentle
when you let me know.
And finally - yes we do spell them "tyres" and when I first arrived in
Australia I couldn't find "tires" in the Yellow Pages until someone kindly
pointed me in the right direction.
Wes
|