Apparently good tyres of a size where there isn't much choice. Not to be confused with 26" X 1.25" tyres, which I'd previously found to my cost to be a different size... I've yet to try them on the road, as restoration project delayed.
Only tire available for the Schwinn s5/s6 rim in US is the Kenda and Sunlite(?) - both are smooth tread for road use. Schwalbe hs130 is the only tire I’ve found that has a more aggressive tread for rail-trails. You have to get it from UK, but it’s worth it. Mounts easily without tire levers.