Welcome to the forum!

I don't have a 3rd gen but there's a few cars that I can think of that seem to fit what you're going for.
@RobMinhas runs 18s.
https://sl-i.net/FORUM/showthread.ph...&highlight=rsk

and @jdmfemme I'm pretty sure runs 18s too.
https://sl-i.net/FORUM/showthread.ph...&highlight=rsk


Rob makes a good point about his 18s making his brakes look tiny, my 2nd gen brakes look tiny behind 17s though. Regardless of what size you get they'll still look pretty small. I personally think the 3rd gens look a lot bigger than 2nd gens, when in reality they probably aren't much larger, but I think 18s suite the 3rd gen nicely.

I'd say if you're looking to eliminate wheel gap and don't want to run a bigger tire then go for 18s. If a taller tire is okay to you then go with 17s, the ride quality will be a little bit better too. If you want a smaller side wall AND 17s, you're probably gonna have to go a little bit lower to bring the tire closer to the fender.

jdmfemme's car actually looks really good on the B4 wheels she has.