Ask A Scientist© Environmental Earth Science Archive

name         Gary B. P.
status       educator
age          50s

Question -   At what temperature does a car tire melt and at what temperature does asphalt 
melt?
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Asphalt binder is a handy material in that it flows nicely when it is heated to around 250 
degrees F, but is relatively solid at room temperatures.  The hot liquid is mixed with pre-
heated sand and stone, then delivered to the paving site promptly.  The hot mixture is spread
and compacted before it cools. When it does cool, it creates a "viscoelastic" material.  That 
is, it acts kind of like a liquid and kind of like a solid depending on the rate of loading.  
The hotter it is, the more liquid-like it gets.

So, it really does not have a melting point like, say, ice has, but it does soften considerably 
as the temperature increases.  To give you a feel for relative temperature, hot mix is 
generally delivered at roughly 300 degree F.

Tires are not my specialty, but I understand racing tires operate well over 200 degrees F.  
I suppose it would be possible for a very hot tire to soften the surface of a pavement under 
the right conditions.

Andy Johnson
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