On Tuesday, October 2, 2018 at 1:10:14 PM UTC-4, Emanuel Berg wrote:
How wide tires can one put on a 622x15C rim?
Currently those on are the accursed 23-622
or 700x23C.

TIA

--
underground experts united
http://user.it.uu.se/~embe8573

You can put any size you want on there. The only problem that could occur is if the sidewalls are very thick in which case there's no room for the tube to expand inside the rim hence holding the tire in place. Not likely for good-quality tires.