The Schwalbe Marathon GreenGuard E-25 Endurance Performance Wired Tyre - 20x1.5 is the archetypal high quality touring tire. The highly elastic GreenGuard layer is 3 mm thick. One third of the GreenGuard is made up of recycled latex products. The "Anti-Aging" sidewall can withstand the typical cracking that results from overloading due to insufficient inflation pressure for much longer.