First off, welcome. Two, not sure why you're worried about a tube back there. These boys have been running the stock rear wheel, tube and tire for decades and, no one seems to have a problem and, they've been running them in some seriously ugly terrain. And many of us, run pretty low tire pressure to boot. So far, in the short time I've owned one, around 4 months or so, I've done quite a bit of off roading (well, at least some) and I've not had any issues with the rear tube. Your choice.