CushCore Gravel/CX Tire Insert - 700c x 33-46mm SingleCushCore Gravel CX Tire Insert 700c x 33 46mm Single. CushCore is an engineered foam insert to be mounted inside a tire designed to absorb impacts reduce vibration and increase lateral stability. These characteristics translate to a more controlled comfortable and faster ride. The system is designed to be used with tubeless ready or tubeless converted rims and tires and is compatible with tubeless tire sealants The insert divides the inner volume of