[aerohead]

It is California state law,that rolling resistance data for all tires sold in the state be provided to the consumer.
You should be able to contact a seller and request the data for your tire options.
Old school logic from the days of GM's TPC was that with an increased diameter/radius/circumference,each individual tread block would visit the road surface less often for each revolution.
Heat generated at the hinges of each block,as well as sidewall deformation would be reduced,as there would be fewer deformations per revolution with the 'larger' tire.
Hysteresis of the rubber itself is an issue,as it determines the amount of entropy(energy lost to friction heating) during cyclic deformation.In a perfect rubber,there'd be no heat generated,but you might not have any traction or tread wear life either.Lots of trade offs.