[rjn21]

You've probably already tried this but, there are 2 parts in the EPC as applicable to the M5 (doesn't mean much as its riddled with errors), but:

6 11 2 182 460 Space saver wheel 4X17 ET:5 with Continental CST 17tyre 135/90R17 104M. It says for dealer use only and not for customer use??

36 11 6 788 203 Compact spare-wheel system 3,5X17 ET:8. Given its BMW’s database, just because it says it fits it may not…..

First pic is the dealer only system. Second pic is the compact spare.