Hello Philippe,
unfortunately, due to the odd tyre size 355 mm, the choice is extremely limited since many years.
The (basic) options are limited too → switching to 16" wheel size / ETRTO 305 mm.
The advanced option are custom wheels with 349 mm (Brompton) rim size, that will multiply the tyre choice 
Tannus are not that easy to mount (and hard to get rid off), just saying…
Last option - you choosed already - ask weirdos at forums 
Cheers,
Chris