I have a 2001 Silverado that I hunt out of and I am currently running 295/70 16's on it with a set of keys and blocks on it. I am thinking about selling my current tires, bfg at's with about 10-15k miles left on them and getting a set of 315's. I know the 315's are about 1.5 inches taller. How much is this going to change my mileage and power?