Tire size vs mpg with an LS

[Billett]

This sort of goes along with my other thread, but I thought it was different enough to deserve its own. I've been considering purchasing an extra set of tires for the truck and had a few questions.

Current tires are 285 wide 28" tall cooper cobras. They are essentially a large passenger car "all season performance" tire. I've had them on plenty of vehicles and like them in general.

Question is, who is running larger 33" or so tires on the street? I know generally a larger tire will cause a loss in mpgs due to more rolling resistance and more aero drag and the larger torque required to move it from a stop. However, these engines are torque monsters, would a larger tire really matter that much if it werent too radical in the tread department. The aero of these trucks is also shot already so I don't think that could hurt a ton... also a larger diameter means lower rpms.

Has anyone here done a tire size change like this? Similar treads, passenger to a/t, anything really. I'm just kind of curious now before I buy another set.