Bone stock (410s) at 55mph my truck will do a consistent 21mpg. At 75mph with the 355s it ranges from 16-17mpg. Towing my enclosed trailer (~3k lbs, but pushes a lot of air) still got 17-18mph at 55 with 410s, gets 15mpg at 75 with 355s. Got about 12 with the 410s at 75.