I've posted over 100 responses to your questions in my first month here. Now I need some help. I just bought a 1980 Ford F250 a V-box salt spreader in place of the bed in back, on a single axel. I'm wondering if I should replace the single axel with a dually because of the weight it will have to carry. It was used by a school the last 14 years so it never had to run more than around their parking lot. They even had a little 3 gallon gas tank to replace the regular tank when they took out the bed. We'll be using it to go from job to job and alreasdy bought a bigger gas tank. The tires are dry rotted and need to be replaced. My friend told me 8 ply 16.5" tires will hold 2700# each (5400# total) and should be enough to carry the spreader filled with salt. I think it's a 1 yard hopper. Would you guys recommend putting a dual axel on there and getting 6 new tires or just keeping it as is with the 4 tires?