Weight is not the only consideration either for mpg's...rolling resistance will have a huge effect. saw on Tire Rack where they ran a BMW with various tire/wheel combos. The lightweight setup did worse than a heavier combo with some eco type tread pattern. I'm guessing a lot of these aggressive off road tread patterns would probably totally suck in the rolling resistance column.
I completely agree. The more aggressive the tread, the higher the rolling resistence.
We can add other parameters as this thing matures.