Jeff Liebermann wrote:

https://en.wikipedia.org/wiki/Rolling_resistance#Primary_cause
A characteristic of a deformable material such that
the energy of deformation is greater than the energy
of recovery. The rubber compound in a tire exhibits
hysteresis. As the tire rotates under the weight
of the vehicle, it experiences repeated cycles of
deformation and recovery, and it dissipates the
hysteresis energy loss as heat. Hysteresis is the
main cause of energy loss associated with rolling
resistance and is attributed to the viscoelastic
characteristics of the rubber.

Wow, interesting!

So the viscoelastic property is what makes the
tire deform/recover as it rolls
in under/away from the weight of the
bike&rider, and this is hysteresis, and the
result is loss of energy (as heat), and this is
one component of overall loss of energy which
is bunched together as rolling resistance?

There's a section in the Bicycle Science 3rd
edition book covering the details of
measuring rolling resistance

I should get that book...

The one I bought on eBay cost me about $20.
You can also get one with a digital scale for
about $40, but I don't think it's worth the
added cost. The difficult part is that it
works best on a flat rubber surface, which is
rather difficult to find on most tires.
The result is that the dial will move around
slightly as you roll the device around trying
to get it to stay flat with the tire surface.

Maybe disintegrate a tire and put a piece of it
in a stand or a vice? Or/and perhaps fixate the
durometer as well, like a shop drill?

BTW how do ISO/ETRTO measure the tire width?
I've heard it is from one bead, over the tread,
to the other bead, this distance divided by
2.5? Do they also disintegrate the tire before
doing this or do they use a string of some kind
to loop around?

--
underground experts united
http://user.it.uu.se/~embe8573