I’m with Den and Mick on this one. My car came with Michelins which I replaced due to their age and sidewall cracking, with the correct spec Michelin Radials.
What puzzles me though and what no one has yet mentioned, is what the pre war Tractions ran on as standard before Michelin started producing the ‘X’ commercially in 1946?
Cats site gives wheel sizes for the different variants http://www.cats-citroen.net/citroen_tractionavant/ta_history_parts.html#wheels but not what actual tyres were used