mileage with new tires
car has trip computer. have had car for 10 years. car gets 26-27mpg on the highway. got smaller tires. 4% smaller. now car gets 30mpg on highway. had them for about 2 months. have hit 31mpg at times. never did that before. so mileage is up about 15% but tires are 4% smaller. i know odometer is off. i can live with that. but why is my mileage so much better?