US Patent 11382432 Step stool with tread

Treads are provided which allow a stepping surface to be made of a rubber, plastic, or other gripping material while limiting or eliminating recesses or corners that are difficult to clean. Concentric rings of alternating hills and valleys are provided on a top surface of a step. The hills and valleys are wide, have limited slopes, and reduce abrupt directional changes in the surfaces. A user can clean the surface easily with a sponge, towel, mop, or other cleaning tool because the cleaning surface can reach most or all of the tread surface.