Re: [Phys-l] Another tire question

[Rick Tarara <rtarara@saintmarys.edu>]

That is a different question--thus 'Another' in this thread I started.

The question below was well answered, I thought, by Car Talk with the help 
of Wolfgang.

To summarize:  The number of molecules of gas don't change, the temperature 
doesn't change, and the internal volume of the tire doesn't really change, 
so the pressure doesn't change.  If the car is REALLY heavy, then there 
might be some measurable change in internal tire volume and therefore some 
change in pressure, but any 'real world' change would be very small and 
beyond the ability of commonly available pressure gauges to read.  (The 
tires squash but bulge when on the ground--leaving the internal volume 
essentially unchanged).

Rick

----- Original Message ----- 
From: "LaMontagne, Bob" <RLAMONT@providence.edu>
Subject: Re: [Phys-l] Another tire question


> I am curious why the discussion has not addressed the original question
> posed way back - Will the tire pressure read differently if the car is
> resting on its wheels versus being up on a lift?
> _______________________________________________