Stans list the following rims with the internal rim width and recommended tyre size:-
Crest 23mm 2.0" - 2.25"
Arch 26mm 2.25" - 2.5"
Flow 29mm 2.35" - 2.8"
Sentry 32mm 2.5" - 3.0"
Baron 35mm 2.8" - 3.2"
Major 28mm 3.0 - 3.5"
I was thinking about buying a pair of 29mm wide rims. Is the above table worth adhering to, or is there more leeway with the range of tyres you can fit (ie can you go much below 2.35" and above 2.8" with 29mm rims)? Perhaps a narrower rim would be better for standard 29er tyres, but I seem to have read of people fitting just about any tyre to wide rims (around 30mm) and saying it's an improvement over narrow rims.
A lot depends on the tyre.
Something with a narrow tread area tends to look like a bald head with a mohawk strip of tread down the middle on a wide rim, other narrower tryes with more distributed knobbles come up fine.
I've run 2.2" mud tyres fine on 30mm rims.
There's a LOT more leeway than that. Not too long ago, Mavic 317 rims (17mm internal) were common as muck and folk were using 2.1" tyres on them.
I guess that's broadly what Stans think is optimal, but as mentioned above, some tyres will be affected more than others.
Mavic did a thing about the various factors a little while ago and published a table of what was "safe" as well...
http://engineerstalk.mavic.com/en/the-right-tyre-width-on-the-right-rim-width/
