Tires: 4 ply vs LT tire, ford f 150, 5th wheel

Question
My 2010 Ford F 150 with Max Towing pkg. came with 275/55R20 tires. I want to pull a 5th wheel with these 4 ply tires which are rated at 2400# each- is that safe? Payload is 1925#, and tongue wt. is 1260#. Truck must weigh @ 5200# plus 160#? for gasoline, 200 for hitch, 320 for passengers.

Answer
brent,

Pickup trucks are rated for towing capacity by the vehicle manufacturer.  If you are towing within those limits, then the tires that came on the truck are adequate for that service.

If not, then you need a bigger truck.  After all, there is the stress on the suspension, brakes, and the frame to consider - in addition to the tires.