I'm running a basically stock 2000 SE 4X4 and am looking into getting the BFG A/T KO's but would like some advice on size. Stock is 265 70 R15 which is close to the 30's - will going up to 31's make a difference with fuel economy? Haven't done the PML yet either - due to this whole gas issue, but have been catching the off-road bug and want a happy medium.

32x11.50X15 or you could maybe get away with 33x10.50X15 on the stock wheels. The 32's fit real well on the stock wheels. Just minor trimming on the plastic that no one will notice. You will want that bigger tire after the pml. I really can't see much of difference in fuel economy especially from the 31's to the 32's. The fuel economy difference between those two tire sizes is pretty minuit, so you might as well go with the bigger tire.

May not be that big from 31 - 32 but again, this still needs to be a daily driver which is already only getting around 14.5mpg city so I want to optimize the happy medium. BTW - have any idea what mpg the white rhino's getting? and... saw some old pics of your beast with the T/A KO's - what did you think - why the switch to M/T's?

I was very happy with my 31x10.5 AT KOs. Obviously they're MUCH better than the stock tires. I was pretty suprised the difference they made on the trail. I couldn't really notice a huge difference as far as gas mileage, but I never really measured it officially.

I see what you're saying, and I was the same way when I first started out. I rocked the 31X10.50 for awhile, and then the 32X11.50 both being the bfg all terrain. I would say that after running both you might as well go up to 32X11.50. Definately recommend the all-terrain though. I just wanted a tire with a slightly softer compound hence the reason I switched to the mud-terrains. The all-terrains seemed to be a little harder, and the rocks were eaten em up. I also wanted to go with a taller thinner tire (33X10.50), as they seem to do well with the terrain we have out here. I am also very interested in traveling to baja and mexico. So, I wanted a tire that could perform in a variety of different terrain. The all-terrains are not the best choice for mud. The mud-terrain has proven excellent. A lot quieter than I thought they would be-not much louder if at all than my all-terrains. The tire wear amazingly enough seems to be about the same. I have done round trips to colorado in them already as well as many other adventures including Mexico and they are holding up very well. All in all you can't go wrong with either in my opinion. Just get them at discount tire with the warranty plan. I have used that bad boy so many times.

I didnt see any change in mpg at all..
stock vs 31's.
I did see a small drop in highway rpm about 150-200 rpm at 65mph indicated.
I love the BFG AT's this is my 3rd set on 2 different vehicles. They wear like steel, ride pretty quiet and work well for all but the nastiest mud.