Hi there,

You can fit any size wheel up around a 205/40/17 with out picking up any problems.

Just a few things to note when changing rims to your VDub:

1. What's the PCD? 4/100, 5/100 even 5/112 maybe? Most Polo's of your range are 4/100.
2. If you fitting aftermarket rims, check the off set as it might catch the brake callipiers.

For your sizes you want to put you need not cehck the above too much as 15" is well within modding.

Hope that helps ... cheers :)