[thstone]

The N rating by Porsche is useless. Don't waste your time giving it a second thought.

Do a search on tires and you'll find numerous threads on the subject.

As mikefocke said, every tire is a compromise. So, Step 1 in selecting a tire is to figure out what you want and what you're willing to give up:

high mileage vs high grip?
quiet vs louder?
maximum dry grip vs everything else?
quick turn-in and corner response vs poor corner response?
all weather vs sunny and clear?
cheap vs expensive

For instance, all I have ever cared about is maximum cornering grip and I am willing to sacrifice everything else (rain performance, noise, longevity, and price) to get it. This narrows all of the selections down to about 3-4 very high grip tires.

Once you know what characteristics you want in a tire (and understanding that you can't get them all and get it cheap), then post back and folks can give you specific recommendations.

And yes, there are a few good "all-around" tires, but the more specific you can be, the better the advice you'll receive.