Tire construction is actually the key to its weight. As an example(only using Toyo tires because I knew they listed each tire weight on its site), the Toyo RA-1 205/55/16 weighs 23lbs. The 245/45/16 in the same tire weighs 25lbs. Nice stiff sidewall and larger tread block pattern.

Toyo's T1-S in those same sizes weigh 21.2 & 21.6 respectively. Moving up to 17's, the closest match I could find to tread width AND overall diameter was 215/45/17 at 20.1lbs and 245/40/17 at 22.3lbs. A 245/35/18 weighs in at 22.9lbs.

As sidewalls are decreased, the material needed to stiffen those walls increases either in mass or material strength... I have no idea which or if both. Either way, it seems possible that by going to a larger rim, not only are you moving a higher concentration of mass away from its rotational source via the rim, but also potentially increasing the weight of the tire- the farthest object from the rotational source.

No, I'm not a physics professor, but I did stay at a Holiday Inn Express.

 

Remember that all these factors play an important role in wheel dynamics. But you also need to factor contact patch into the final equation in terms of overall benefit.

 

I agree. I just didn't see where they were concerned with traction, and failed to think about resulting rolling friction.

Additional friction generated by a larger footprint would have less affect on losses than the rotating mass itself.