TiAgX5's point about tires/wheels and load is worth considering. I know opinions vary about wheel appearance, and I won't dive into the deep end of the 'wheel offset' pool, but, depending on how you use your X5, I'd be careful about putting 'sportier' M3 wheels on a 3.0 X5 if its used, as mine is, as an upscale bavarian sport tractor [occasionally pulling a 5k+ trailer load]. Safety first!

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2006 X5 3.0 6-spd w/Evo UUC ssk
sport/premium pkgs
born Valentine's Day, 2006.