Subtle meaning of 「役目を果たす」 I just wonder what does mean exactly? I know that this phrase roughly means "to perform one's duty". But does it also imply that the duty at issue will be fulfilled and so will be exempted in the future, or does it have no such connotation?

does imply that the role that was given is now fulfilled, and that it will not be performed anymore. E.g. if you say then the implication is that the tyre has expired and cannot be used anymore.