I think it probably depended on the town and location, just like today's sidewalks. A business district walk was probably wider than a residential one, and I wouldn't be surprised if it also varied with the width of the street. Narrow streets probably had narrower walks, because there'd still have to be room for wagons and carriages to get through.
If you have a particular town in mind, it wouldn't be surprising to find that the modern sidewalks are the same width, to avoid changing easements and traffic patterns.