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Old 06-09-2008, 08:46 AM   #9 (permalink)
tasdrouille
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First, congrats on your reading. If only more people would do what you did...

Let's just look at rolling resistance alone for a second. Why does a railroad steel wheel on steel rail has a RRC of roughly 0.0005 (according to wikipedia)? Because the hysteresis of both the wheel and the rolling surface are very low. Cover that steel wheel with a layer of rubber and RR will increase becauseof the energy lost in the hysteresis process.

Now lets switch back to tires. Although there is a significant amount of hysteresis happening in the tread (that's why as tires get used the RR goes down, less tread material, less hysteresis), the vast majority of the hysteresis happens in the sidewalls. If you increase the pressure of the tire you effectively reduce the property of the sidewall to flex as the tire rolls, hence reducing hysteresis losses.

As for everything else I'll have to go back to check the studies as I don't remember getting to the same conclusions as you.
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