Hello and welcome.
I have many years of experience with the high end vehicles.
I want to introduce you to OZ racing wheels.
The OZ racing wheels is compatible to the Quattroporte.
Although the rear the wheel is wider than the front wheel. It will be OK for temporary fitment in case of a puncture.
It is the same bolt pattern (5-114) all around. Therefore it will be OK to install the wheel in the back.
Please let me know if this help you out.