The preferred ratio between the riser/" class="glossaryLink" data-cmtooltip="093a97d9f1c1659c73676219edacc7f7" blank" >target="_blank" >riser and blank" >tread of a stairstep, specified by either of two formulas: R + 2T = 24 to 25; R x T = 72 to 75. (Ching, 1995)
