Nope. Just "Rios". "Rios" = "more than one Rio". "Rio's" = "the following thing belongs to Rio". "Rios'" == "The following thing belongs to more than one Rio".

"All three of my Rios have died. My most recent Rio's scroll wheel broke. I think that the Rios' quality is not very good."

Apostrophes are (basically) never used to pluralize. (Only in the case where the thing you're pluralizing is an abbreviation, like "PC's", and even that is very often frowned upon.)

Of course, it can also be used to abbreviate "is", like "Rio's" = "Rio is".

"This Rio's a piece of junk."