Now it`s DUB...

The 20's aren't the problem. The backspace on those rims is all wrong. The car would look a lot better lowered, but I doubt that's going to work. Based on the backspace those wheels aren't going to clear the fenders or the quarters if it's lowered any from the current ride height. 255's and a 4.5" backspace is going to rub, plain and simple. Not sure how wide those wheels are, but I would bet you need at least a 5.25" backspace to run those 255's inside the fenders. The backspace on the 275/35/18's on the front of my Duster is 6.1".

Personally I think the 20's are too big for the front, I think an 18/20 combo works well because you can match the sidewalls by running a taller tire out back. That way you can keep the front wheels and ~26" tall and avoid cutting the front corner back so much. That allows a 27 or 28" tall tire out back, and you can lower the car enough to tuck the wheels into the fenders, which is what looks good with the larger rims.