Does 1SB Adventure Pkg affect MPG?

[HummerHippy]

Hi all -
would like your input. I am looking at 2 - 5 speed H3s. ONe with advenbture pkg and one base model. I test drove aventure version. I understand it'll be slightly rougher ride on the road. But I am wondering about the gas milage. larger tire makes me think slightly better mpg, but a corser tread makes me thik slightly less mpg.
thanks