This is the handiest online tool you can have for deciding what offsets will work:
wheel offset calculator 
Your new setup essentially shifts the entire wheel inward by 4mm, meaning you have 4mm less clearance on the inside of the rim and 4mm less extension on the outside of the rim.
IMHO, 4mm won't likely cause your problems BUT you haven't mentioned what size tires you've gone to. Perhaps you've changed the overall diameter of your rim/tire combo? As you increase rim diameter, you need to decrease you're tire's aspect ratio (sidewall thickness) to maintain stock diameter.
This online tool will help you determine the dimension changes resulting from your choice of tire sizes:
tire calculator