I would definately get a tire that is better at preventing flats, especially since you are in the city where sharp objects are abundant. Try using something with puncture resistance engineered into the tire. The tire that came stock on my Surly Long Haul Trucker has those qualities. Here is a link. I would still try and keep a patch kit and a multitool with built in tire tools handy just in case. I haven't had a flat yet on my bicycle and its coming up on 1 and 1/2 years with no flat.

http://www.biketiresdirect.com/produ...t-tire-26-inch