I was wondering what everyone else was getting for city im getting around 13 so i was just curious if that was good... ive heard tire size can change milage but i only have 285/75/r16 on the truck
you can always buy a handheld programmer and recal your speedo. I know htat 285/75-16 is 7% bigger than the stock tires. Check out this one: http://www.miata.net/garage/tirecalc.html
According to that, if you are running a 305/55-20, your tire is 9% bigger than stock. So, you would add 9% to your miles shown on your odometer and then divide that by the gallons used.