New to 27.5+ but enjoying it so far. Have some Nextie 50mm wheels with 3.0 tyres on, working v well. Interested if I wanted to go for a narrower tyre come mud and winter, how narrow can you go. Presumably the shape of theatre is influenced by the width of the rim? How does it work with wider rims?

Just thinking ahead and needing to learn more!

Ta

29+ and 2.4″ maxxis ardent here, although on 45mm internal it goes up to 2.55″.
I wouldn’t go narrower than this, because of the rim edge would be exposed too much, and tyre profile would be square(ish).

For 27.5+ there are so many 2.8 or 2.6 tyres that I really wouldn’t go for anything narrower than that.

Depending on the bike, I have low BB issues on 3.0 tyres, if you go smaller you will be dropping the BB as well.

Stans, Mavic and Bonty have tyre size/rim width charts that might be worth a look at (google image search) I’ve had 2.75 on 50mm Hugo. Not sure if I’d want to go a lot narrower than that. Depends a lot on the tyre itself. some will show a lot more sidewall than others. There might be some 2.4s that would work.

a spare set of 29er rims would be your best bet, I reckon. More £ than spare tyres, but it would be much more satisfactory! you could even have them set up in the summer with some big road slicks for occasional road/bridleway bashing

Some further reading on theatre shape:

http://theatreprojects.com/files/pdf/Resources_IdeasInfo_typesandformsoftheatre.pdf