Originally Posted by
PTbiker
The problem is that I thought I had an "MTB only rim" (since it's from a mountain bike), but what matters is where I ride. So, in conclusion, I can use 30 to 50mm tires, as I've been riding on road only. If I use my bike for MTB, I should use at least a 47mm tire to protect the rim, right?
One more chart:

Source:
https://www.schwalbe.com/en/reifenmasse
If the worst you’re doing is gravel or fire road type of dirt roads I bet you can get away with 35mm. If you’re doing something where you know the tire will hit a sharp hard edge like a boulder or tree root then bigger tires can help.