They won't match. To give you a general idea, 10-15 years ago, most road rims were around 13mm internal width (18 external) and run with 23mm tires. I run "28mm" tires on a set of rims like this, and they measure out to around 26.5mm wide when mounted.

There are some charts floating around from tire and rim manufacturers that purport to tell you what sizes you can safely use together, but for liability reasons, they are extremely conservative.

One thing worth mentioning is that, even though a wide tire/narrow rim combo will not be as wide as a wide tire on a wide rim, it'll still be nice and tall, giving you better compliance than a short, skinny tire.