Here is how I replace my tires. In my game, I replace my existing tire for empty tires to simulate a flat tire feeling. After replacing the certain tires with my empty tires. I remake the tires by running the follwing:
GetVehicleMovementComponent()->WheelSetups = EmptyWheelsSetup;
GetVehicleMovementComponent()->CreateVehicle();
GetVehicleMovementComponent()->RecreatePhysicsState();