74 Duster rear tire fitment options.

I've never had a rub issue with a 255 on that rim...

I’m pretty sure he has a 7.25” or 8.25” rear, they’re significantly shorter than the 8 3/4’s and even the stock backspace wheels can have issues with a wide enough tire. Based on that picture it doesn’t look like he’ll have enough clearance to go to 255’s. They’ll rub the springs.