If you are worried about performance remember to get a wheel that is less than 20lbs so it won't be heavier than your stock ones. I will be getting sub 13lb 15 x 7s for my Corolla. Most 15s are 15 x 6.5 though
For all-seasons that have good wet and dry traction and some snow ability check out the Dunlop SP Sport A2s. You can read the reviews of them at www.tirerack.com. They are inexpensive and perform very well.
Your fender gap will not change because when you get bigger wheels you get a lower profile tire so the over-all outside diameter is the same.