Tire Rolling Resistance Increases as the temperature drops!

[CapriRacer]

Originally Posted by Vekke

If that is your picture on your pages are you able to make lines sideways to make it easier to interpret? ......

That graph is lifted directly from this paper:

https://azb4fstg-cdn-endpoint.azuree...2.pdf?ext=.pdf

Originally Posted by Vekke

..... That test is done at rolls so only tire temp is effected on those results? ....

The paper doesn't actually say they allowed the tire to come down to the temperature indicated, but not only would that be the logical thing to do, they comment on the rubber behavior at a range of temperatures, so not adjusting the pressure for the temperature introduces another variable and makes their comments about rubber behavior at lower temperatures a non-sequitur.

Further, they tested on a new piece of equipment, so the temperature is the temperature of the room. The test would generate some heat in the tire, but that is not accounted for. It's never accounted for in tire rolling resistance testing, because that's the way tires are used.

Originally Posted by Vekke

........ So less air drag will come on top of those savings yes or no?

I thought lower temperatures result in MORE air drag, not less. But, Yes, the vehicle and all the drag associated with operating the vehicle (such as air drag) are not part of this test.

[aerohead]

Technically, we'd want to calculate the local air density based upon all local parameters.
Online calculators spell out all the necessary data requirements.

[aerohead]

On page-6 of the Smithers report the author says that all laboratory tire testing is conducted 'AFTER' the tires are warmed to ambient equilibrated temperature.
So it looks like there is no 'Cold-Start' tire testing conducted.
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At least as early as August, 1979, tire manufacturers were aware, and reporting that, ' A tire at ambient temperature may have 40 percent more rolling resistance than when it's fully warmed up to temperature.'
'Cold cars use more fuel.'
And, the colder it is, the longer it will take for a set of tires to come up to whatever the equilibrated temperature is, for any given temperature.