The nimbus sport tyre has a smooth tread that rolls fast and serves as the perfect fit for any rider looking to get around town there are many widths to accommodate different models riding styles and comfort levels while the blackbelt flat protection found here adds confidence for riding over rough city roads and bike paths casing 60 tpi bead wire compound 70a flat protection blackbelt 650b x 23 psi 25 50 approximate weight 760g