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If you are thinking in this direction there is a specification for tires
called rolling resistance that you may find interesting.
Basically it is a measurement of how hard it is to get the tire rolling.
Here is a link
http://en.wikipedia.org/wiki/Low-rolling_resistance_tires
http://www.treehugger.com/files/2005/05/low_rolling_res.php
Kinda wish they would add this spec to the sidewall of tires.
Have Fun !
RichC
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