wheels - back to basics
...The wheels are only 8.5" wide with +45 offset.... Just make sure you don't go too wild with the width and offset and you won't have issues.
Hey,
Thought I'd jump in with a few comments for iRG in case you weren't getting the full picture.
Things to think about:
Bolt pattern
width and offset
effect on ride/handling
All the RECENT** Golfs, Jettas, and Passats have the same bolt pattern (5x112). This is an absolute. You must have the right bolt pattern. **(slightly older golf and jettas had 5x100).
They also have a positive offset. You can get some funky wheel that has too little or too much offset (not a vw wheel, but some inappropriate aftermarket wheel). You could put them on, they might run, they might mess up the handling. So while it's possible, don't do that.
As VeeDubFreak points out, "Just make sure you don't go too wild with the width and offset and you won't have issues."
Which brings me to diameter and thus ride quality/handling. You asked if 19" was a big as you could go with these cars. Remember that as the wheel gets bigger, the rubber on the tire gets shorter (lower profile). You can get bigger wheels to fit. It's back to the width issue that will get you, as the wider wheel will rub.
But regarding big wheels and low profile tires, there's a diminishing return as you get bigger and bigger and a worse ride quality to suffer with. All of this is a balance.
For me, that means the biggest I'd put on your car is an 18" wheel. It should offer you snug handling without knocking you around too much. 19"? I personally don't see the point. 20"? I'm starting to laugh.
I hope this helps paint the bigger picture.