Rough treads are used to generate friction and get a grip on rough surfaces.
(Rough treads; are used; to generate friction and get a grip on rough surfaces) (Rough treads; to generate; friction) (Rough treads; to get; a grip on rough surfaces)
Rough treads Rough treads Rough treads
are used to generate to get
to generate friction and get a grip on rough surfaces
friction
a grip on rough surfaces