I can't say that I know off the top of my head exactly what hub it comes with, but it's cheap and easy to swap out the hubs. If it comes with 5x5.5" just go to Tractor Supply or the Internet and order up some 5x4.5" hubs. Don't let the lug pattern be your deciding factor on whether or not you get a trailer.
You might also consider the Lifetime Tent Trailer, which I wound up choosing over the Jumping Jack. They're both made by the same company, but the Lifetime is sort of a Jumping Jack 2.0 - it's a little smaller when in trailer mode, a little bigger when in camping mode, it's lighter, it's cheaper, and a lot easier to tow off-road especially behind smaller vehicles like your Jeep or my Suzuki. The most significant downsides are that it carries 1 ATV instead of 2, and it doesn't have as many optional factory-built accessories. But yes, it comes with a 5x4.5" lug pattern. :wings: