I am thinking about putting these on my X it is my wife's daily driver. I am concerned that this is too much tire for the gear ratio to get the mpg's I'm looking for. The 31's are to small so that my mpg's are suffering now. If you are running these and have average gas mileage specs let me know. I have 4.10's and 31's and get about 15mpg. Befor the 4.10's I had 3.73 with 31's and got 18.5. I don't want 32's because they are 11.5 wide.