Quote:
Originally Posted by Ernie Rogers
Thanks, Racer,
So, I conclude that all else being equal (including coefficient of restitution or internal friction), I can reduce the strain energy and therefore the energy loss by using softer rubber (lower elastic constants) in both the casing and the tread material. Of course, thinner components are also desired.
I am over my head here-- adding a second phase to the rubber, such as colloidal silica, could act to "pin" movable elements in the small-scale (e.g., molecular) structure thereby reducing internal friction. (This is called dispersion hardening in metals.) While hardening may occur, this could actually be detrimental.
Comments?
Ernie Rogers
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I think you will find that rubber plays a very small role in overall tire stiffness compared to the ply cord and steel cord - and those play a small role compared to that of inflation pressure.
For practical purposes, the rubber, especially the tread rubber, comes along for the ride - and the rubber's role in Rolling Resistance is large simply because of its volume percentage.
Rubber chemistry is not my strong point, but my understanding is that silica is a substitute for carbon black, and the RR improvment is due to less internal friction.