I think I may have found the answer to this issue myself.
From what I can guage, these rims are the E53 X5 4.4i BMW LA wheel, V spoke 63, which are 9JX19 ET:48 & 10JX19 ET:45. From what I can figure out, these offsets are going to bring everything too far into the car without the use of spacers. So how big can you safely / sensibly go with a spacer?