Originally Posted by Warrior3313
Yea I mean I know the tires throw the speedo off but I wouldn't think by 4-6 mpg.
Sure it would.
Like the other guys said. It's a few things.
1- The speedo is off so your mileage is off.
2- your truck is now taller. Airflow underneath it lowers mpg
3- heavier unspung weight from the new tires lowers mpg's
You can get rid of number 1 if you try.
Get it reprogrammed or use a gps unit to find your actual miles and hand calculate the mpg's.