You want to be very cautios using P rated tires on truck, especially a 3/4 or 1 ton. If the rated capacity is too low, the tires can blow out on you. You also need to stay on top of the tire pressures, which will have to be run far lower than what the OE truck tires would run due to the lighter construction. Load capacity will be greatly reduced, potentially to just weight of the truck plus passengers depending on tire size/rating.
