i'm in NYC too... and i recently swapped to the OEM 214s staggered from the stock 18s...

no problems at all...i'm actually liking the ride even more... feels more planted and i don't notice a difference when hitting potholes..

i do have all-season non-run flats though.. and that's probably why it feels a little better than the stiffer run-flats..

the 18s were Ok.. but these are definitely better..

19s would be a good combo.. if you go with the straight non-staggered setup you can rotate them... and you'll get better traction in winter..(if you go with all-seasons)

if you're going with summer only tires then go for broke and get the 20s with the staggered setup... then swap back to stock wheels with winter tires...

i'm too lazy to swap back and forth so i have 20s with all years..

been doing this for a couple of years with no problems...

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2012 X5 50i M-Sport
2014 X3 35i M-Sport