I run taller and
narrower than stock tires on my 2000 4Runners - 235/85R16. One set of Duratracs and one set of BFG ATs. There is no significant change in gas mileage corrected for the diameter. Actually both runners speedometers are spot on with this configuration.
They steer lighter due to the narrow contact area and they do really well on the snow and ice. My perception is that they bite better and tend to plow less, particularly in deep wet snow and slush. They don't rub either.