What size wheels and tires could I put on this 1957 Custom Royal

IMG_2562.JPG IMG_2557.JPG In sure you will get 15's on it, as i mentioned in the other thread the truck diff was wider and the stock wheels still fit.from the looks of rear wheels they are too far under the car in my opinion.
59 regent was what i was playing with. If i recall the truck rear was near 4" wider. I used wheels originally on car.