I've never had a 19" wheel on a daily driver before my 997...even my 996 had 18s. I haven't really had a lot of complaints with rough surfaces. You're obviously going to feel more vibration and jolts, but as long as you buy a HIGH QUALITY, STRONG wheel, you won't have any issues. I have a set of OZ Ultraleggeras in 19x8.5, 19x11...I lOVE them. Go with the 235(f)/295(r) combo, or if you're going to upgrade to the 305/30/19 rear, I STRONGLY suggest upgrading to a 245/35/19 in the front, vs. the 295/40/19.

Here's a pic of my car on the OZs...like 'em!

 

I'm with NJ on this one ...