Recently I bought a pair of CST 27" x 1 3/8" (37-630) blackwall tires for a future project. The looked larger than the ordinary 27 x 1 1/4" like Kendas and such. I mounted one up today on a NOS replaclement 27" wheel. The steel rim measured 25mm outside 17mm inside.
Inflated to 70psi (max 85psi) the max width was 35mm with an aspect (height of ~30mm. As a reference a mounted Pasela 37-622 measured 36mm.
It will likely be easier to sell these older bikes with wider tires. Only $24.99CAD (after inflation, pun intended!) A mid seventies Peugeot tourer will get them for sure.




Meaty looking tire.

Pictured with a recent steel arrival with 27 x 1 1/4 Kendas