I wouldn't suggest running a lower profile tire on 15's for street driving... recommended is 195/55/15... so I think anything else would make the car much lower and throw off the speedo. Actually, They don't make a 195/40/15... at least not that I am aware of. The only 195/45/15 tire I found is Kumho. There are more options for 195/50/15 sizes. I would say a 205/50/15 is a safe bet.
If you want lower profile tires, then just get 16" wheels.