^Read this thread. It answers your question perfectly.
Originally Posted by MangoTango34
Stock, largest tire is 32. And i think for wheels you can go down to 15s
Plenty of folks run 33s stock, though they will rub the fender flares if you flex the suspension offroad.
Originally Posted by mayajverona
And what size wheels should I go with? I've seen a lot of 16s for sale but I feel like that's too small...any help would be appreciated!
Many run 15" wheels on Wranglers, though you just have to take care to get the appropriate backspacing or they'll rub the brake calipers.
Otherwise, this is like asking what color pants you should buy. There are hundreds of choices, all of which are perfectly reasonably. It's a matter of preference.
In general, most Wrangler owners stick between 15" and 18" diameter wheels. 15s, 16s, 17s, and 18s are all reasonable choices. 20" wheels--unless you're going to accompany them with 40" tires--tend to get a little big to be practical offroad. They tend not to leave much sidewall for flexing and get damaged as a result.
Otherwise, up to you.