What year Duster?
I had to trim my rear 1/4 panels on my 1971 Duster (removed) 3.0 inches on the front side and 2.0 inches on the rear to make 315x60x15 on ten inch wide rims fit it
I had a younger guy come up to that car at the Mopar race at Woodburn dragstrip back in 2008 or so and look at the car real closely and make the comment you can't make that size tire fit on this car, he said he had one and he could only make a 275x60x15 inch tire fit on it
I told him to step back and look real hard at my car and tell me what he saw, I then told him when he didn't see what was done to it to make them fit that I had stretch the rear wheel wells five inches and moved the rear end forward one inch to make it look stock
My message is you can make a larger tire fit if you want to do the work