A 235 squeezed down onto a 6.5" wide rim wouldn't be any wider than a 225 on a 7" wide rim.
Not to be contrary, but are you sure that those are 235's in those pictures? Because they really don't look tall enough to be 235/60/15's. A 235/60/15 is 26" tall, and that height by itself can cause clearance issues. Especially on a Duster. Even with 225/60/15's I barely had enough clearance to the front and rear corners of the wheel openings on my Duster. I had to max out the front lower fender brace to clear them and they were VERY close to the rear lower corner of the wheel opening on turning, and they're only 25.6" tall.
These are 225/60/15's on my Duster. Maybe it's just the pictures but the 235's in your pictures look smaller than these, not larger. The sidewalls in those pictures look shorter than these. You can also see that even with the additional backspace these wheels are pretty far out toward the fender, the top doesn't look terrible but I was running -1° camber too. At the bottom of the fender you can see the tread was outside the corners.
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That's not true at all in the front. In the front the Dart actually has MORE room, the wheel opening is further back so it eliminates the clearance issue to the rear corner of the opening.
In the back, yes, the Duster's have a wider wheelhouse. But that's not really an issue with anything smaller than a 245 on a Dart.
In the front can see the difference here, first one is is a Duster fender, second one is a Dart fender (for my Demon conversion). Clearance to the front corner is the same, but clearance to the rear corner is greatly improved. Width of the fenders is the same.
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