Quote:
Originally Posted by Deslock
From what I've read, though the force required to offset rolling resistance isn't related to velocity, at high speed the additional heat increases the coefficient of friction.
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The extra heat is not the cause, it is the effect. Rolling resistance isn't caused by friction, but rather by hysteresis in the rubber. Basically, as the tire rolls forward and a certain patch of rubber comes into contact with the pavement, that rubber gets squished and stores up energy like a spring. As the tire continues to turn and the patch of rubber starts to lift off of the pavement it pushes away from the road and releases most of the stored energy, most but no all. The difference in energy has been absorbed by the tire as heat.
If I had to make a wild guess about that exponential velocity component, I'd say it comes from the viscoelastic nature of rubber. The faster you try to squish it, the harder it is to squish, and presumably the higher its hysteresis becomes.