An aircraft's number of wheels generally ranges from just three to over twenty.
An aircraft's landing gear is one of its most essential features. As the name suggests, the component is responsible for both safe landings and takeoffs, supporting the plane while it is on the ground or taxiing. The design of this feature is extremely important as it must be strong enough to hold up an aircraft, yet it also affects the plane's weight, balance, and performance. In many airliners, the landing gear is retractable to ensure the aircraft has optimal aerodynamic performance while flying through the air.