205/50-15 is fine. So is 195/55-15.If you want a really sticky tire on dry pavement, then get the Falken Azenis RT-615 in 205/50-15. Another excellent choice, even better than the Azenis, is the Dunlop Direzza Sport Z1 Star Spec in 195/55-15.
I don't know if you're referring to the KDW or the KDWS. The KDW/KDW2 is really overpriced and you can do a lot better for the money. If you're considering the KDW2 because you want better traction in rain and/or longer treadlife, then you may as well get the Kumho SPT. Its performance is very similar and you can get the SPT for only around $44/tire in 195/55-15 at tires-easy.com, which is about a third the price of the KDW2.
The KDWS is an all-season tire and it doesn't make sense to get an all-season tire in your case. Unless you plan to use these on snow, in which case you may as well get the all-season Kumho ASX for half the price.
