I have just bought an original 550i rim online, and i kept one of the tires when i put new ones, so i am gonna put that tire on that rim ( which is a run flat tire, gonna be a spare) all i am gonna need is a wrench and a jack from another BMW.
Now that i thought about it, if i turn the spare face down in the trunk, you can put small stuff inside to keep it from going all over about in the trunk.