Rim Size

[Cstout90]

hello,

So ive been looking for rims for my brothers 2011 ford fiesta. and the more i search and research the more confused i get. im told such and such is the right size but theres apparantly leeway on some of the specs. And a lot of postings i see on craigslist and the like only list the car they were off of.
im wondering if anyone can tell me cars share the wheel size to the 2011 fiesta, or maybe a range of sizes that will work. or even a website with this information. thanks a ton in advance!

Cody