My points here are (1) the LR4 traction control system is incredibly good, and (2) hard street tires did fine on some level 5 or 6 trails.
I took my stock 2013 LR4 to Death Valley the first week of November. The two most demanding trails I took were Dedeckera Canyon heading south from Eureka Dunes to Steel Pass, and going down from Mengel Pass heading east from Barker Ranch.
I was running fully inflated (36 cold psi front and 42 rear) Toyo Open Country H/T all -season 255/55 R19 light-truck street tires. I will attach a photo showing why I opt for hard tires. It shows the deformation of a 42 psi tire on a small rock. Clearly, airing down would have put the sidewall in contact with the rock. In the past I ruined all four original tires by airing down in Mojave and Death Valley (Continentals as I recall).
The LR4 in low-range rock-crawl mode pulled smoothly and surely over the steps in Dedeckera Canyon and Mengel Pass: no lurching, sliding, etc. Easing down the far side of a rock was like gliding. My only difficulties were self-inflicted. Luckily I was with an excellent spotter. (Justin M., who comes to some of the club MORGs in a black 2-door Wrangler with plates "MI6 D6").
So, those running street tires take heart.
My sidewalls look unscathed, BUT one front tire now has a pinhole leak in the sidewall. The leak is tiny -- found only with a soap-bubble test. There also appears to be a ripple in the sidewall between the leak and the rim. This looks more like a manufacturing problem than like rock damage to me. I am open to argument to the contrary.