What is the largest wheel's I can put on a 1974 dodge dart 360 sport

N50-15s on 10s;About a 13" section and 28 tall
The modern equivalent might be 325/50-15s
The hard part will be to get the correct offset wheels.
With the springs in the stock location, the tires will have to stick out past the bodyline.
With the offset kit,and a narrowed rear end, I managed to get them into the allotted space on 4.5bs wheels.

But it don't make a difference in straighline work on a streeter; the tires still spin to past the speed-limit.
And 295s fit easier and keep the back in the back, and are easier to power-slide with.