i know the 35 inch tires are throwing the speedo off. I drove around town alot today and the truck averaged 16.2 in town. I have 325/65/18 tires, which are 35 inch tires , How much mileage am i getting. Sorry about 2 questions back to back, but i am caught up with this truck tonight

 

are u hand calc? its about 1/10 mile off to the mile. so if it reads 200miles its about 220miles.........i average 16. can get 18.....can get 14

 

Depends on the gear ratio and original tire size the speedo was calibrated for.