Sometimes a narrow tire on a wide rim helps with cornering because the wheel makes the tire stiffer. Lot of autocrossers try to do this if they can in their class. I know a guy running 15x8s with 225/45x15" tires.
When you have a wide tire on a narrow wheel it makes the car handle funny and sometimes like cray. Turn-in is poor and it feels like you are driving on rubber balls.
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