I have been reviewing tire threads and gear ratio threads ad nauseum here and at other forums, but can't seem to find a solid answer to some questions I have. Is there any sort of scale that will allow me to see how much MPG will be affect by going up from a 29" (Stock JK) tire to a 32" or 31". I am getting a new set of tires/wheels and am shopping around, but don't want to suffer too much in an MPG drop. Thoughts? I would really like to go 32 (265/70/R17) BF Goodrich All-Terrain T/A KO on 17s with around 4.5 BS to get a wider stance. Does stance affect performance and MPG either?

Thanks,

Brian