It should be noted that riser and tread size ultimately depends on step
use. For a stepped ramp walkway on a long slope, the riser height
should be limited to 6" (150mm) and the slope between 1/8" (3mm)
per foot and ¼" (6mm) per foot. In general, wide treads are
compatible with a short rise because it allows for a more natural
walking stride. Risers and treads must be uniform in any given flight
of stairs.