flat tire vs pneumatic tire

flat tire and pneumatic tire both are nouns.

Word	Noun	Adjective	Verb	Adverb
flat tire	Yes	No	No	No
pneumatic tire	Yes	No	No	No

As nouns, pneumatic tire is a hypernym of flat tire; that is, pneumatic tire is a word with a broader meaning than flat tire:

flat tire: a deflated pneumatic tire
pneumatic tire: a tire made of reinforced rubber and filled with compressed air; used on motor vehicles and bicycles etc

Other hypernyms of flat tire include pneumatic tyre.

flat tire (noun)	pneumatic tire (noun)
a deflated pneumatic tire	a tire made of reinforced rubber and filled with compressed air; used on motor vehicles and bicycles etc