Wheel Offset Calculator
best i can do without seeing your setup and my limited knowledge of that vehicle.
If you have 7" wheels on your car now and are going to an 8" wheel you loose 3mm of inner clearance and add 23 mm extention outward from your fenders.
If they are both 8" then you are pushing your wheel 10mm out like using a spacer bascially. not too bad an idea on most VWs...
BTW, i like those wheels man, good luck.