Gravel / Gravé / Gnarmac / Groad / ATB

They do recognise that here though:

The wheel size is essentially a unicycle standard. There are literally only a few people making rims and only one tyre manufacturer for serious off road use. The technology in tyres has definitely not filtered through to 36er tyres just yet, and it’s one of the concerns we have when wanting to take this into some of the remotest, most inhospitable areas on the planet.