Tiren is a Daimon Heart Snatcher who was sent by Kaorinite to extract Pure Hearts. As she was created from a motorcycle, she has a tire in her gut, which she can use to drive like a motorcycle. She can shoot rings at people, and chain them together as well. She can also create a clone of herself. She appeared in Sailor Moon S Episode 9, Friendly Foes.
Kaorinite created her from a biker's motorcycle to extract a biker's Pure Heart. This, however, was bait to destroy Sailor Neptune and Sailor Uranus. She chained Sailor Moon and Sailor Uranus together, but they were able to fight together. Sailor Uranus destroyed her clone with World Shaking, and Sailor Moon destroyed the original Tiren with Moon Spiral Heart Attack.
Her name is based off the word "tire".