In the mid 70's some Gitane Tour De France bikes came OEM with 700c clinchers as an alternative to sewups. Weinmann rims(not concave, but the ones with dimpled spoke holes) and 700c versions of the then ubiquitous Hutchinson " Facon Main" gumwall tire. I remember concerns being voiced by some in the shop about finding replacements for the "oddball" sized tire in the future!
Best regards,
Wes Gadd
Unionville,CT