Truthfully, its difficult for them to do this. They would have to find someone else who wants to swap wheels or order you a new set of wheels which YOU would pay for. They dont have the luxury or the flexibility of altering the standard issue equipment. If this was years ago and there was several thousand dollars in the car for them, they'd probably work with you but they're making nothing on you as it is. Unfortunately, your request is just a headache to them. I say they let you walk if you stand firm. I also highly suggest the sport pkg. Living in Manhattan doesnt mean you wont benefit. The 19's arent any different of a ride than the 18's and a sport pkg equipped car just looks and feels so much better. Good luck

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2013 F10 ///M5 (ED 11/2)
2013 X6 50i Msport
2008 Smart
2012 Jeep Wrangler Unlimited