width of the tire is based on width of the rim, not diameter (I'm guessing you meant 17" diameter).
look here for a sample chart of tire width vice wheel width:
http://www.tirerack.com/tires/Spec.j...el=Pilot+Sport
As to if the performance is better - way too complicated for me to answer. There's MANY variables, sidewall stiffness, tread compound "softness", % of tread contacting the road (from slick to ??), and of course road conditions enter, i.e, snow, rain, dry performance. There's lots more, mostly I think this is a trial and error thing - look at how many tires the big companies bring to an event or even how Bridgestone has teamed with Ferrari on F1 to match tire to chassis characteristics - science and black art - IMHO.