Get the same brand and model tire for the replacement. As long as the existing tires aren't worn more than 50% it should be fine. If they are worn too far, you can get DSC/ABS errors from different rolling diameters. In that case, you can get the new tire shaved down to match the tread depth of the existing tires at the tire shop.

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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