I had replaced tires a few weeks ago and was successfully able to stack the set of OEM-sized wheels and tires on my W124...
...unfortunately, putting them into the trunk was a waste of time, as the car was on jackstands at the time...just wanted to see anyway. So I threw them into the ML.
On a different note, if you have non-OEM wheels but the OEM spare, try putting the spare on with the lug nuts you have. I found that the lug nuts the PO purchased with the wheels were too short for the OEM spare...that would have not been fun to discover had I been away from home with a flat tire!
