I've been constantly having problems with my wheel going flat. I couldn't find anything on the rim but I changed the rim tape and I bought a new tyre.
The old tyre was a bit worn. It was also fitting the rim too easy, something I was attributing to the fact that it was old and also that I've been changing the tube a lot. Nevertheless, now I noticed that the new tyre also goes a bit too easy, as in, I didn't even have to use any tool to put it.
I am sure they are the right size and I don't see any evident sign in the rim to make me think it is not usable anymore, although it is a bit hit here and there but nothing particular as to make anyone think it shouldn't work fine.
Is this normal? Should I check something else?
EDIT: The tyre size is 37-622. It is a city (Grandma/Grandpa-like bike).