The Schwalbe Marathon is very well protected against punctures thanks to its GreenGuard insert made of 3 mm highly elastic natural rubber. It enjoys a strong reputation as the original and progenitor of all high-quality touring tires. The GreenGuard emphasizes sustainability, as it consists of one-third recycled latex products. Its lifespan is extended by anti-aging sidewalls that endure typical overloads from insufficient air pressure for a long time before developing cracks. The Schwalbe Marathon is fundamentally suitable for e-bikes up to 25 km/h (E-25), with commonly available sizes also approved for faster e-bikes with support up to 50 km/h (E-50). - 26 x 1 3/8 / 37-590 = E-25 - 26 x 1.25 / 32-559 = E-25 - 26 x 1.50 / 40-559 = E-25 - 26 x 1.75 / 47-559 = E-50 - 26 x 2.00 / 50-559 = E-50