I put on some 35's and using a handheld gps I've determined that my speedo is off buy about 10%. So does this mean my mileage is of by the same 10%. Also would the fuel efficiency be off by that much as well. I know I am actually traveling further that the odometer reading so the mileage is better than the truck thinks it is getting. I was just wondering if the amounts are equal to the speedometer difference. Also somewhat related has any one had any difficulty with the warranty with larger tires with the dealer saying there are more miles on the truck than actually registered. Since the warranties are mileage based 50 000/100 000 miles etc.