The French Wikipedia in "Éditeurs français de cartes postales" lists the following:
Bougé-Béal, éditeur-libraire à Clermont-Ferrand (Puy-de-Dôme), 25, rue de l’Écu.
(See an example here).
Dumousset, éditeur à Clermont-Ferrand. (So far I have seen only views from this publisher).
Durand et Cie (Veuve), éditeur à Clermont-Ferrand sous le sigle VDC.
(See an example here).
Garel (Ainé), (Bazar), éditeur à Clermont-Ferrand (Puy-de-Dôme).
(See an example here).
Another producer was Merel-Gourgouillon, Clermont-Ferrand, 1 rue de l'Ecu. (See an example here).
Clermont-Ferrand was the home of the Michelin brothers whose tyre business was incorporated in 1899 and who built a factory in the town (or towns, there are still two downtown areas).