I bought this set from Tischer BMW (http://www.trademotion.com/partlocator/index.cfm?action=MorePartInfo&PartID=876046&siteid =214672&catalogid=4462) and it fits the storage perfectly. Did not actually test the spare in action, but it is exactly the same size as the spare size recommended on the car door sill.
The spare tire storage in my car was lined with the fabric but underneath the carpet fabric was everything ready for installing the wheel bracket. The set includes all the parts provided when ordered from the factory at the time of car purchase. Very easy to mount the spare under the cargo floor, it is secured to the car body (in case of rollover). Not sure how good the supplied lifting jack is, however all the parts are OEM.
Recommend getting this set if you can justify the cost. $335.00 plus shipping + tire mounting (tire comes separate from the wheel, so you have to mount it). It is a bit pricey; however for me this was the only option how to get the OEM spare tire here in Canada.