Quick search. Note that you need to use F25 in your search, not X3.

There are aftermarket wheels available, and spacers. Those both specify the wheel dimensions. It has also been a topic on several boards.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue