I currently have 175/70r13's on my Sentra. I am getting 39ish to the gallon doing 63 miles one way to work everyday. My curiosity is if I upsize to a 195/75r14, as I have a chance to purchase a whole set tomorrow, will it help or hurt my gas mileage. My mind says it will help, as the revolutions per mile will drop, but all the forums I read on it says it will hurt mileage. Some one help me figure this out
