Tires are measured to a given dimension.
For example
255/75-17
255= Tires section width in millimeters
75= The two-digit number after the width, separated by a slash, indicates the tire's height as a percentage of its width. In this case the height of the tire is 75% of its width.
17= Rim size
Lastly, a tire is designed to carry a certain load.
With this in mind, it should be understood a tire size of 255/75-17 will be very similar in size regardless of the brand or vehicle it came off of.
With this said, a Ford Bronco Big Bend has a 255/75-17 tire in stock form and it has a curb weight of between 4297 and 4467 lbs.
In comparison.
The curb weight of a Jeep Wrangler JL (2-door) Willys is around 3,948 pounds, while the Jeep Wrangler JLU (4-door) Willys has a curb weight of 4167 lbs.
To answer your question, Yes a set of take-off tires from a modern Ford Bronco will fit onto your Jeep Willys and be safe in doing such.
In addition, these tires will very likely perform better on the street than the tires which came on your Jeep from the factory.
What you will be giving up is some offroad capability and some subjective appearance of a knobby tire.