As far as being quicker or slower off the line, a smaller diameter tire will be quicker. I would assume, but have never tested myself, that the larger diameter tire will increase your top speed. One reason to change to a larger diameter tire, and probably a good argument right now, is for fuel mileage. The larger diameter the tire, the less revolutions per mile it will make. I guess it will depend on how much larger you go over stock as to what kind of gains you will see. Hope this helps you out!!