245 is the width of the tire. You want a thicker sidewall
from the 17" tire. Example, if a tire is 245/40-17, the 40 dictates how tall/thick the sidewall is. 40 means 40% of the width, which in this example is 245mm.
You want to keep the overall diamter as close to stock as possible. This tool will help you compare: http://www.rimsntires.com/specs.jsp
These aren't 17", but if you want a nice setup that's right at $1200, I'd recommend these. The wheels are on closeout and the Contis are a good Max Performance summer tire.