rear wheel doesn't fit in spare wheel well

[noworyz]

This sucks - had a flat, and the rear wheel (20" 315) doesn't fit in the back. It's bad enough that i had to unload the car on the side of the freeway, but it took me 10 minutes extra to figure out that the floor pieces do not fit over the wheel as you would expect them to. After just floating the pieces above the wheel (not anchoring them down), the floor raised almost 4".
This is just bad design - how can you design a wheel well that doesn't hold your largest OEM wheel?
To top it off, i had to drive 50mph on a ridiculous spare for 2 hours!
Anyone with possible solutions ...? Do 20" run-flats work?
(This is now my biggest issue with the X5!)