That's a large weight gain for a small increase in tire size. Are the smaller tires P (passenger tires) and the larger LT (Light Truck)? Or are both the same type?
I went from a P to an LT on my Silverado. Even though the size was the same and I could run higher tire pressures, the weight went up and fuel economy went down (even after they were broke in). Between those two options, the smaller is likely the better of the two.
http://ecomodder.com/forum/showthrea...hts-19698.html