I actually put new tires on the back. EVERYtime. Even on my RWD vehicles, new tires to the rear, bald tires scrapped, better used tires to the front. Studies have shown regardless of FWD, RWD, or AWD in a case of hydroplaning you are less likely to wreck with better tires on the back, and more likely to not even slide with better rear tires.
Plus I don't want to slide unless I mean to, and which point, I want it to be RWD with enough power to keep it sliding as long as I need.