Most fire engines are equiped to Cary 500 gallons of water weighing in at 4200 lbs. Leave room for at least another 1000 lbs of equipment and 800 lbs of personnel you have 6000 lbs you would need room for. So 18000-6000 gives 12000 so I would guess some where between 9000 and 12000 lbs bare bones truck tank box & pump no tools ladders or hose
