The back way to Black Canyon City is a BLM off-road 4wd trail that travels parallel to the Black Canyon Trail's hiking network. It's very skinny in spots, being only one vehicle wide in areas where passing cannot be accomplished easily. In other areas, passing most likely will require both vehicles going slightly off the trail while avoiding any cacti plants that could puncture even the toughest rock crawling tires. The southern half is otherwise not difficult as you drive on well-packed dirt through gentle curves and hills. However, further north, especially around Slate River, you'll find larger rocks, looser dirt, tighter turns and steeper hills. There's even a few hundred foot long section of the road that was chiseled out of a steep rocky hill-side. Four-wheel drive is definitely a must, and some spots may even require a locker and/or a traction control system depending on the driver's and the vehicle's capabilities.
AZLRO promotes safe off-road driving, supports the "Tread Lightly" program is active in maintaining access for off-road driving as we explore all the great state of Arizona has to offer.