OE Style 214s should slap right on...the OEs are staggered.
X5 E70
10x20" tires: 275/40R20 offset ET 40
11x20" tires: 15/35R20 offset ET 37
Good BMW OE Wheel site:
Felgen-Katalog - BMW-Treff - der Treffpunkt für alle BMW-Fans und -Fahrer
OE style 214s and tires to fit, are not for the faint of heart, budget-wise...
GL, mD