And thats going to be really big and you are going to be spending big bucks on tires.. And ofcourse wheels are also an issue. Nothing really changes other than you need 20x10 for the rear and 19x8.5 for the front. You are going to be limited in your choice for 20" wheels unless you can get someone to sponsor you.
Personally I think you are taking your car the wrong direction. And 19" is the max I would go and that would only be for the rear.