Breakdown is a thing of the past. The punctureable tyre: the SmartGuard insert made of highly elastic special rubber is particularly strong. It provides retracted foreign bodies such as shards and granules lasting resistance. Even a retracted staple cannot puncture the protective layer. The SmartGuard insert is rolling resistance neutral. The Marathon Plus rolls as easily as a tyre without a protective belt. Please note: use a pressure gauge for the Marathon Plus to adjust the air pressure. Thanks to the special design, a pressure test by thumb is not sufficient