Ordered one of those for the front of the 1500 Drifter, since it was listed as a front tire where I found it. It is actually an either end (non-directional) replica of a 1940s Firestone. If you ride in the wet, stay away from zig zag tread. If you ride across bridges with metal grate decking, avoid zig zag tread AND straight rib tread (Avon "Skid Master" or similar).

Period correct 15 inch tires are very hard to find, most of them were Carlisle or similar Firestone clones. Shinko is alright, if you could find VS800 Intruder spec Dunlop Qualifiers you'd be better served (sand off the outline white letters, dye the sidewall black).

Try running a 90/90-19 and a 130/90-15. The rear is easy (Kenda) the fronts almost impossible to find. And you'll only find the rear in modern tread at that.

Worth the time and money to have your hubs relaced into 21 and 16 inch hoops. Hundreds of retro choices in 80/90-21, 90/90-21 and 130/90-16.