Seriously?

You really think that what's inside the tyre is irrelevant?
Would a tyre filled with ice feel the same as one filled with water?

You're half right about the interface between the road and tyre being what matters, but it seems to have gone completely over your head that the purpose of the pneumatic tyre is to manage that interface. To provide a contact patch capable of providing traction, the tyre deforms. That flattening of the tyre occurs at the road/tyre interface, and since the wheel is rotating that means that once per revolution every point on the tyres circumference is compressed against the road and returns to normal shape again. That requires energy and THAT is the primary source of rolling resistance. Whatever is compressed is therefore a factor in rolling resistance. So, unless you're using tubeless, the tube is a factor.
You seem to be under the impression that only the outer contact surface is relevant. That is utterly wrong as I hope the above explanation makes clear..
Weight is of negligible importance by comparison.

Do the seat coverings deform and produce a reaction resisting the rotation of the wheels? No, they do not. That analogy is utter nonsense and simply reveals that you don't understand the mechanism!

Can you explain why rotational weight is so important?

You better believe it -- esp if it's 100F outside and you're wearing shorts and running naugahyde seat covers. Like an egg on a frying pan.

Ok, I get it. Latex tubes bounce back faster, thus deform less, thus better marginal rolling resistance.

But over non-IM distance, for a rider of 150lbs (me) who keeps inflation @100psi+, over quality roads, is the marginal gain anywhere near the gain from lighter rotational weight?
I'm guessing not.

You're guessing wrong, then. This has been tested and measured many times over. Conservatively, latex will save you 3 watts per wheel over butyl. That's not a small savings.

Rotational weight? Once you're up to speed the difference is tiny.

If only there were a way not to guess, if only there were a way to measure the actual effects ... nah.

It's a good thing we have physics, math, and actual measurements then...no guessing necessary!

And you're guessing wrong :-/

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http://bikeblather.blogspot.com/

Are you referring to the Panaracer R'air latex/butyl hybrid? I've been riding these for years and they perform well.

Measurements show that they are roughly halfway between standard butyl and latex in terms of rolling resistance. expect them to save 1.5 W if latex saves 3W.

In terms of puncture resistance they are at least as good as standard butyl and much better than thin butyl. They require no extra care like latex does. I haven't had a pinch flat with them but have had the standard thorn and nail-type flats. They are easy to repair

You'll get a wattage savings with them, not as much as latex but without the hassle of latex.

Puncture resistance is as good or a bit better as standard butyl but with lower Crr and ~30% lighter

Wattage savings is the same as thin butyl but those thin tubes are flat magnets and these are not.

I had way too many unpredictable failures from standard latex (never had a tube last more than a few months) and decided they were not worth the trouble. The Panaracers are a good compromise, IMO.

http://www.active.com/...ight-vs-aerodynamics

http://www.analyticcycling.com/WheelsConcept_Page.html

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"...the street finds its own uses for things"

Another 'like' for you.

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Developing aero, fit and other fun stuff at Red is Faster

Well, no need for me to pile on I suppose, the others have already said it, but since I'm here.....your guesses are not serving you well, you're guessing very, very wrong.

As I said in my previous post and others have said in theirs, weight is not terribly relevant whereas the tube directly impacts rolling resistance. The physics/maths and testing all demonstrate the same thing. It should not be controversial!

The hierarchy of importance from highest to lowest for most riders and conditions should typically be:
Aerodynamics>Rolling Resistance>>Weight

Lower speeds increase the relevance of rolling resistance, steeper gradients increase the relevance of weight. But a course needs to be fairly extreme, or other considerations fairly unusual to change the above order of relevance.