What are wedge shaped radiating treads on stairs known as?

Wedge-shaped radiating treads on stairs are known as winders. Winder treads are used in stair construction to create turns, allowing the staircase to rotate without requiring a landing. These treads are narrower on one side and wider on the other, which helps change the direction of the stairs while maintaining a continuous ascent. This design is particularly useful in spaces where a standard rectangular landing would be impractical, enabling a smooth and gradual transition at the corner or midpoint of the stairway.

Understanding the term "winder" is essential for recognizing various stair designs and configurations in residential construction. The other options refer to different components or types of stair construction that do not specifically describe the function and shape of wedge-shaped treads used for turns.