At 08:19 AM 8/30/2010  -0700, Don Hanson wrote:
>  Water vapor (humidity) is present in atmosphere. Water boils, changing into
>steam at 212f.  As the water vapor inside a tire turns into steam (race tire
>inside temps regularly exceed 212f)  it expands dramatically.  You know,
>like a steam engine?

Don, water vapor *is* steam, or vise versa.  Since there's no phase
change you don't get any extra expansion beyond the normal expansion
of water vapor as it gets hotter.  If you're starting with liquid
water that's a different story.

Yours,
David