Hmmmm.... U have also owned a Supercourse and Grand Prix from 1986, which is when they went Reynolds 531 butted main tubes. Sure enough catalog says 555 for the Olympian. Misprint in catalog or the label, or maybe an intentional mid year switch? Nice that you can squeeze in fat tires. The Supercourse and Grand Prix maxed out 700c x 25c ( brake clearance issue).