1971 Duster, will an 18X8 wheel work on the front and what’s the largest wheel/tire combo that will work. Asking for a friend.

Falls into the category of "you can make anything work if you try hard enough".

Most folks can't get a very big wheel/tire combo on an A body since they, #1 Don't want to cut anything and #2 Aren't willing to buy custom wheels with the correct offset.

How much work do you want to do? I believe 72bluNblu on FABO has 275's on the front and 295's on the back of his Duster with 18 x 9.5's. If you measure pretty well and roll/cut the fender lip you can fit a big tire back there.

9"rims on A body scroll down to post 3_
Build thread big wheels/tires show up near the bottom of the thread. Nope not my ride, but....

I have 275-35-18's on 18x9 wheels with +35 offset on my Duster on all 4-corners. In the front, it's necessary to push the front fender brace all the way out and also trim the fender tab in the back of the wheelwell some and replace the bolt with a pan head.

My car also has a B-body rear axle and the Dr Diff Mustang cobra brakes. With stock brakes, chances are you'd want a 5-10mm thick spacer for the front at least.