Grigg, I think those tanks are going to be bigger than 50 gallons. For many years I ran 22" tanks round tanks. A 57" x 22" is around 100 gallons with 90 gal draw. If they are 100 gallons, that will be 1500 lbs hanging from the side of the frame. For quite a few years it has been law that fuel tanks are marked for gross and draw. I now run 26" tanks because it gives me a little more room between the tank and the drive axle.