CushCore Gravel/CX Tire Inserts - Fits 700c x 33-46mm PairCushCore Gravel CX Tire Inserts Fits 700c x 33 46mm Pair. 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 A specially designed tubeless air