it IS a tire issue. a few months ago (lol when my car was drivable) i needed some new tires but i didnt have a lot of $$. so i just replaced the fronts cause they were the worst..my rears prob had like 15% tread left on them.
BAD idea. i got caught in rain, hit a little puddle on an overhead expressway..my front tires gripped well but my backs went hydroplaning all over the road..after about 5 seconds of trying to control the car it finally just went crazy and i spun around over 3 lanes and smacked the barrier with the driver's side of my rear bumper
didn't have a lot of damage (just a LOT of scratches..one deep enough that it scratched all the way through the urethane to make a small hole) but it did scare the living HELL out of me. and fortunately i didn't hit anyone..i think everyone saw me struggling with it and kinda laid back so when i lost control everyone was a little behind me. it was crazy..i didnt want to drive for weeks after that.
as you can think..i immediately replaced my rear tires and i hadn't had an issue with them even in the rain.