James Bond , oh I mean 007x3. now I know what you are after. you are trying to make the x3 look like a X5. mean and meaty.. Your Tires sizes could be over kill, you may end up messing up your transfer case.
I would revert back to the normal set up, plus it might interfere with the manufacturers warranty and in case your transfer case starts to act up which could be SOONER than you think BMW will not cover.