I hope not since BMW offers 19" wheel/tire packages as an upgrade option on both the X5 3.0 and X5 4.4i
Per Owner's Manual
- 17"
- - Front: 255/50 R19 103V
- - Rear: 285/45 R10 107V
Ensure your OEM wheels are of the correct offset and width.
Be sure you use the correct tire size listed inside your driver's side door or listed in your User's Manul for safety reasons as well as warranty reasons.