In a message dated 07/23/2002 7:43:54 AM Central Daylight Time,
cartravel@pobox.com writes:
> Subj:Re: Tyre Pressure/Temperature
> Date:07/23/2002 7:43:54 AM Central Daylight Time
> From:<A HREF="mailto:cartravel@pobox.com";>cartravel@pobox.com</A>
> CC:<A HREF="mailto:fot@autox.team.net";>fot@autox.team.net</A>
> Sent from the Internet
>
>
>
> Ok, I tried to be quiet, but my chemical engineering background won't let
> me.
> Air in your tires (or nitrogen, argon, hydrogen, hellium, whatever) obeys
> the
> ideal gas law, PV=nRT. The tire volume is fixed, so the absolute pressure
> increases in direct proportion to the absolute temperature. Let's say you
> have 20 psi in your tires at 70 degrees F. The absolute temperature is 70
> +
> 460 = 530 degrees R and at sea level the absolute pressure is 20 + 14.7 =
> 34.7. If the temperature drops to 50 deg F (510 deg R), the pressure will
> drop to 34.7(510/530) - 14.7 = 18.7 psi. If the temperature increases to
> 130
> deg F (590 deg R) during a race, the pressure goes to 34.7(590/530) - 14.7
> =
> 23.9 psi.
>
Amici:
This stuff is great. I am memorizing it verbatim, and plan to use it a
cocktail parties. While I am totally unqualified, I love to talk Hi Tech.
Can anyone tell me how VIAGRA works. Someone told me it was 2% nitrogen, .5%
argon, 3% hydrogen, 6% helium and 88.5% Fix-a-Flat.
Seriously, I appreciate this thread. We've been playing with tire pressures
for years, and while we look really cool with our clip boards, pyrometers,
and tire gauges.....truth be told..... we're still just 'playing with tire
pressures'.
Years ago the big muckity muck in BFG'S Competition Department (I forget his
name), lectured me on tire pressures for about twenty minutes, and then said,
"In the final analysis it is VERY PERSONAL. You have to run what feels good
for you."
I think the latter is especially true at our level of competition. FORMULA
ONE we ain't.
Bill Dentinger
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