Who is at fault when making a you turn to the right and some one hits the car while turning on the back penal and tire?

This will depend on what Country you are in and the side of the road you drive on there.

1st: "U" turns a dangerous and have to be done carefully and in a lawfull manner.

In North America the Car making the U turn is almost certainly At Fault. A U turn to the right is not Leagle to do.

In England or Austrailia (for example only) we need to look at was the U turn Leagle in that location, Was it done from the correct lane, was it done having signaled properly and so on.

If the U turn was 100% leagle and done correctly the Car striking from behind is at fault.