How wide a tire for my 17-in wheels?

[socratic]

This summer I may be replacing my tires. I'm looking to see if there are ways to make the tires fill out the wheel wells a bit. I've seen some Audis and even Jettas with not too wide a tire but they fill out their wheel wells really nicely. My stock sized tires, in particular the rears, are much wider than the Audi/Jetta tires, yet they look slightly anemic in the 986 wheel wells.

I love the look of my 17-in S wheels (in my 01 non-S) so changing wheels is not what I'm looking to do.

I'm thinking of getting the widest tires that will safely fit into the 17-in wheels that I've got.

That and/or perhaps some spacers.

In the past there was the "Plus 1" concept of increasing the width of the tire but go down a bit in sidewall size (e.g. in a previous car, I went from 155/75-13 to 185/60-13 on the same rim--something like that, I can't remember the actual numbers). That was what I was leaning toward.

What would be some things I could do to flesh out the wheel wells a bit.?

How wide a tire can I put on my 17's? Front? Back?

I should say that I drive spiritedly but don't race nor will I track the car. So unltimate grip isn't a big issue for me. In fact, I'd like a more comfy and quiet ride and/or good rain performance rather than ultimate grip (I'm including this info in case that could affect peoples' comments).