I dont know much about the Hardbody but the TItan wheel/tire is way larger. I assume they have the same bolt pattern but they may not physically fit without rubbing something. Plug those tires sizes into a tire size calculator and it says the Titan wheels/tires are 6.5 inches bigger in diameter and almost 2.5 inches wider. The offset of the wheel will determine where that added width sits.
Not only are the Titan wheels and tires heavier, the larger diameter means the Hardbody has to do more work to turn the tire one revolution. Between the increased size and weight, I"ll bet the truck would feel noticeably slower.