Abstract: A retractable caster wheel for a trailer in which the caster wheel is mounted on the tongue of a trailer for swivelling movement about an upright caster axis and also for swinging movement between a lowered support position and a raised storage position, and in which the caster axis remains upright during swinging of the caster wheel between its lowered and raised positions. The caster wheel can be positioned and used at positions intermediate its lowered and raised positions to support the trailer tongue at different heights and mechanism is advantageously provided for positively adjusting the caster wheel between its lowered and raised positions.