Depends how much the truck in question will haul. We have a fairly light truck capable of hauling 27 tons while being under the legal 80,000 lb limit. That's about 4,890 gallons. I have a few 6,500 gallon tanks and obviously have plenty of room to spare. Our tanks are 2" but that's just how they were already, if I was choosing I would definitely go 3". Sprayer and tanker are 3" and the difference in speed of pumping is very noticeable.