cant remember the offset for the 182, i think its around 45 though, but i'm probably wrong.
Basically, to cut a long story short) the larger the number (et45 is a 45mm offset), the further in the arch the wheel will sit. The lower the number, the more the wheels will stick out.
Wrong offset CAN improve handling, it can also upset it. It may, and probably will, cause problems fitting the wheels, particularly if they're 7" wide. Wrong offsets can increase bearing wear aswell.