I'm thinking about putting a bit wider tires on my mountain bike, but I'm having problems distinguishing facts from fiction about minimum required inner width rim for a tire. I have two mountain bikes with pretty narrow rims: 17 and 18 mm inner width. There are 2.1" wide tires (with tubes) on them and I had no problems. When I look at the tire manufacturer websites, e.g. https://www.maxxis.com/catalog/tire-468-140-minion-dhf, it seems that my rims are way too narrow for any of their tires. Their recommended inner rim widths start at 25 or 28 mm for a 2.35" tire I would like to get.
On the other hand, the rim manufacturer goes with much narrower requirements, e.g. https://cambriabike.com/products/mavic-xm-719-26-mtb-disc-rim?variant=32343195746378 claims that 19 mm inner width is good for 1.3" to 2.7" wide tires.
Is it safe to mount 2.35" or even 2.5" wide tires on my 18 mm inner width rims?
I found this page with tire/rim compatibility chart, which is more lenient, but warns about sub-optimal performance of a wide tire on a narrow rim.