Those trucks were not designed to carry that much water and those tanks make that truck extremely top heavy... Check the NIOSH reports and you will see that a lot of fire fighter deaths have resulted from driving these style of MILITARY rigs as tankers..
I know, this is off topic. When my dad was in the trucking business over 20 years ago, he had an idea for extra wide tires to replace duals. He made the mistake of sharing this idea with someone, and now he kicks himself every time he sees a set on a rig because someone made millions. Moral of the story? Keep invention ideas to yourself. Lol