GenRight's website mentions they have wide fender flares, but I don't see any on there for the JK. Just stock width and a narrow size. It looks to be the same with Poison Spyder right now too.
I hate to throw this out there, but River Raider is the only company I know of that sells tube fender flares wider than stock (two sizes +2" and +4" wider), but they're way over priced and probably full of bondo.
Bushwacker also sells their pocket fender flares in a wider size than stock, if you're into that look. (Personally, I'm thinking about getting their flat fenders, but they're only stock width).
Also, I saw something on facebook about an Australian company called Uneek 4x4 that is working on 1" and 2" spacers for the stock fender flares. I'm guessing they should work for aftermarket fender flares too, but I don't know how good they would look.