Hi. I'm having 33x12.5x15 BFG KM2 as for now. And I think I have nothing more to do with my engine, double checked everything, replaced lot's of things, and I still have bad mpg. Currently it is 8mpg in town and around 10mpg on a highway. Also I do have a big roof rack which i think may play role in fuel consumption. Right now the tires are inflated with 2 bars and are very stiff on road.
So my guess is maybe I want too much and it's usual fuel consumption with such tyres. Please, write your MPG if you have 3.9 petrol engine and 33" tyres and more. Thank you very much.