just been out and the roads wet and my car literally slipped around a corner

( felt like it came from back passenger side )
the tyre on the back passenger side is bald, meant to get it done when heat shield was removed but havent got time to get in as yet.. and cant change it myself as i havent got a locking nut
cant be beacuse of 1 tyre tho can it?
brakes need doing too, grinding and squeeky in reverse
ill go in in the morning to get the tyre.. but is it likely to be that? i put the kids in the car daily and now im a bit worried
shelagh x