Final answer:
The tread of a stair should be designed according to safety standards, which historically have been about 5 diameters wide side-to-side and 7-8 diameters deep from the narrow edge, but newer suggestions recommend as much as 8 diameters side-to-side and 15 diameters deep to ensure greater safety and comfort.
Step-by-step explanation:
The tread of a stair, in architectural terms, refers to the horizontal part of a step where a person places their foot. The standard dimensions for a stair tread vary, but typical measurements are consistent with safety and comfort. According to historical guidelines, an older rule of thumb suggested stair treads should be about 5 diameters wide from side-to-side and 7-8 diameters deep from the narrow edge. However, newer standards have increased these dimensions to provide greater safety, recommending as much as 8 diameters side-to-side and 15 diameters deep. This reflects a shift towards wider and deeper steps to accommodate a greater range of foot sizes and walking patterns.
For example, if we take a 'diameter' to figuratively represent a basic unit of measurement such as a centimeter, this could translate to a stair tread being 20 cm wide and 15 cm from the narrow edge, extrapolated from an example where a jogger covers a staircase where each step's width (w) is calculated as 0.2 meters (or 20 cm) and each step's height (h) as 0.15 meters (or 15 cm). Though the example is metaphorical and actual construction standards will be based on specific regulations, the concept of proportionality in stair design is crucial for ensuring user safety.