The inner section of the rims houses a pendulum that enables for the weight to always situate itself at the lowest part of the car. This enhancement of the center of gravity will undoubtedly help us to overcome obstacles thanks to the additional grip that it will grant us with. You can spin the rim/tire as much as you like but the bulk of the weight will always remain at the lowest piont thanks to an internal bearring. The pendulum comes with the bearings and rapid movements, including abrupt actions are controlled by the way of the bearing oil. We can observe in this video by Uri Valdés, how they are constructed from the inside and how they operate once installed on a Crawler Axial Scorpion.