Flat and thin wheels. Part of a German boys' pre-war picture-story about exciting adventure travel in Higher Dimensions, accidentally sent to an English soldier at the Kut front (wrong address... he tosses it on the ground, disgusted). In the 4th dimension, you can see two aspects of any object at once (well, that is one way of putting it, you'll have to Read The Book... if I can just find the other pages)... that's why we can see the wheels just like this.