How incredibly stupid will this be if I do this? Dont want 20s because of the price and tiny sidewalls. 18s in the front would be nice for the extra cushion, and 19s in the back would fill up the wheel well nicely. So, dumb idea or has other gen owners done this too?

 

Not stupid at all. It's uncommon in the tuner scene, but you see a lot of classic muscle domestic guys doing that. If you can find a set of wheels in 2 different sizes and the appropriate tires to go with them, then do it up!

 

I was going to 19s in the front and 20s in the back but it was cheaper to just do 20s all the way around.