Hmmm... I seem to recall seeing Michelin radials at the Honda dealership in Alameda around 1974. They were being used on a trial basis on CB750 police bikes, but didn't pan out on wire wheels in a tubed application. I seem to recall the issues being squirrelly handling (probably due to the tall aspect ratio on a vehicle that leans) and ctastrophic sidewall failure in the event of a puncture. Maybe they weren't successful, but I think that predates Pirelli's "inventing" claim by about a decade, and Michelins intro of a viable radial by a decade-and-a-half!
mr****.
mr****.