Big Tires and Fuel Economy

This interview explains that bigger tires will not generally save on gas. You might get better fuel economy with bigger tires at constant highway speeds of 60 or 70 miles per hour, but that will be more than eaten away by worse gas mileage at lower speeds. Typical driving patterns will see the vehicle starting, stopping and operating too much at these lower speeds. So most probably, unless you do long highway hauls for a living, bigger tires will cost you extra gas.