The wheels have  smooth hubcaps on the external-facing side, which aids aircraft aerodynamics.

轮子的外侧有光滑的轮毂盖，有助于飞机的空气动力学。

Other improvements include better aircraft aerodynamics, changes to ways aircraft taxi on runways, and the use of lighter materials.

其他改进包括更好的飞机空气动力学、改变飞机在跑道上滑行的方式，以及使用更轻的材料。