that yellow explorer is running 33X12.5 BFG muds
i talked to perry and thats what he reccomends for his fiberglass kit, that kit fits 33's real easy, but some people will run 35's
i would run 33's with that kit myself, because it would look fine work fine and get better gas mileage and stuff like that but if you want 35's it would take like a 5 inch lift and other trimming / modifying. im pretty sure you can run 33's with that kit alone no lift is needed nor any other modifications.
thats a sweet kit though.
peace