1970 Duster wheels

It's very unlikely the 235's will fit without rubbing. The problem is that a 235/60/15 is 26.1" tall tire, which is already pushing it for clearance with the height and width. Next is the backspace on the front wheels. It's unlikely those 15x6.5" even have a 4.25" backspace on them, probably more like 4". Even with a 4.25" backspace, those 235's would stick out a full 1/4" further than the 275/35/18's I run. And I rolled my fender lips to clear the wheels and cut the lower front corner of the fender back to clear when turning, so going an extra 1/4" further out wouldn't work at all.

I did run 225/60/15's on my Duster on 15x7" cop wheels which have a 4.25" backspace, and they were very close to rubbing. My car sat a little lower than stock at the time, and ride height is a factor. I only know of one person that runs 235/60/15's up front, and that's @AJ/FormS. But that's on a Barracuda, and the wheel openings are a different shape and the fenders may be a bit wider on a Barracuda. Ride height is a big part too, I know his car isn't lowered much.

In the back if you have an 8 3/4 with BBP axles the 15x8's with a 4.5" backspacing and 275's should work. It's a tight fit so some cars may need some adjustments based on body tolerances, but that's the typical wheel specs folks run on 15x8's with 275's for a Duster.