---- Don Hanson <dhanson928@GMAIL.COM> 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?

>but when the tire temp goes past
> the boiling point you get another dramatic increase in internal pressure as
> the water vapor from that compressed air turns into steam...more or less,
> depending on what the relative humidity of the compressed air in the tire
> might be.

If your street vehicle (or racing vehicle for that matter) tires are exceeding the boiling point of water at the pressure inside the tire, wow, you got real problems!  Nitrogen in the tire won't fix those other problems (though you won't have any steam).

David McNeely