So those figures are stock? what about with the larger tires, where are you at there? I know I get just about 15mpg on my tank with 33's. I do have to make the compensation though, or it looks much worse.

I get around 255-270 on the tripometer for a tank, at about 19gals. That would equate to only 14.2mpg, but when in reality, with the larger tires I am getting 265-290miles to the tank(about a 7% increase although it might be more around 9%) That gives me 14.2-15.2mpg(during the winter)

You will always get worse mileage in the winter, it is just a fact. The gas is processed differently so mileage drops with it. Just keep that in mind.