Assertion: skate's wheel | /r/MadeOf | polyurethane
Facets:
value: usually
type: DEGREE
Source sentences:
text: The wheels of a skateboard are usually made of polyurethane, and come in many different sizes and shapes to suit different types of skating.
text: Five years later, in 1973, there was a renewed interest in skateboards when wheels made of polyurethane were introduced.