Tyres for cargo bikes, for racing wheelchairs, for exclusive use on the racetrack or tyres with less common wheel diameters can all be found in this category. The size specifications in the ETRTO information give millimeter-exact information on whether the tyre fits, while the design specification describes the construction of the tyre. The range here extends from the non-punctureable solid rubber tyre to the uncompromisingly reduced tubular tyre.