How much of a difference will 11lbs make in a tire?

How much of a difference will 11lbs make in a tire? I need new tires soon and have my heart set on the Grabber AT 2. I want the 265/70-17 but the 265/65-17 are 11lbs heavier. How much of difference will it make with braking and whatnot? Will it affect MPG even more than the weight was the same? Will I be able to notice the unsprung weight? Sorry if these are stupid questions.

 

I could tell a slight difference when I got mine. As far as mpg, not much difference. In the warmer months with stock tires I averaged 19. With the grabbers I get 18.

For me, the winter gas kills my overall mpg. In the winter months i get around 16-17mpg