Infiniti q45 rear wheels go left and right

Infiniti Q45 1992

The rear of the car moves in a baffling manner, like a pendulum. The front part of the car is secure on the road the back half of the car swings left and right! A suspension problem??WHAT’S UP WITH THAT??

The most likely cause for the rear end to wiggle back and forth is because of a belt seperation in one or both rear tires.

Tester