Why couldn't you load ags? The size might vary some, so perhaps less weight, but I doubt you would notice that much difference.
You can certainly fill ags and i would not own this size tractor w/o filling tires no matter what they are.. A 43" industrial is taking on 45 gallons of Rim Guard. I do not know what an 11.2 ag can hold but my 9.5x24 hold around 20. Perhaps the larger ag can hold 5 or 6 more gallons. I think you would notice a difference especially if you are trying to lift something heavy. The loaded ind tires make the tractor weigh 500 lbs more than the loaded ags which in my mind is not so easily dismissed even if the ags provide more traction.