Well with the 17" tires you will have mre fun driving the car because the tire's sidewalls don't flex as much causing the car to be stiffer. This only occurs during spirited driving. The only possible dowsides to getting the 17" tires is that if you enjoy a perfectly smooth ride then you will not have that any longer. The smaller the sidewall on the 17" tires the more you will feel in the road. But, if you're anything like me you will appreciate the added road feel with the larger 17" tires because you feel more connected with the road. Also 17" tires are generally more expensive to replace.
If you're planning on driving with the same tires all year round you might be better off staying with the 16" wheels and tires. When driving on snow you want the tire to flex as much as possible so that the tire surface conforms to the shape of the snow underneath it to give you the most traction. The larger sidewalls on the 16" tires will do this better.
If it was me I would get the 17" wheels with good summer tires, and buy some cheap 16" wheels and snow tires for the winter. this way you are getting the best of both worlds. All season tires work half as good as summer tires in the summer and half as good as winter tires in the winter. So in closing here are the pros and cons:
Pros 17"
- More sportier feel
- Look that much better
- Improve handling
- Improve road feel
Cons 17"
- Not as great in the winter
- more expensive
Pros 16"
- Better all year round tire
- cheaper
Cons 16"
- Look worse
- Not as good for spirited driving
If you want to learn more go to www.tirerack.com. Hope that helps!!!