Tire height help

I am shopping for tires and trying to decide what height to go with. I am currently looking at 225/70/15 for the rear and 225/70/14 for the front. I am looking at the taller tire because I have 373 gears and I'm thinking a taller tire will be more rpm friendly on the interstate at 70mph. What are you guys thoughts and suggestions. I see Lot of you guys run 60 series tires is there an advantage over the shorter tires? From my research i found a that a 225/60 is 2 inches shorter than a 225/70 what would the difference be rpm wise on the engine?