It’s surprising how much flotation you can get out of a 235/85/16 BFG All-Terrain in soft sand—even under the mass of an HJ78 Land Cruiser Troopie—if it’s properly aired down to around one bar (14.7 psi). At that pressure the contact patch elongates significantly, providing vital surface area without the frontal resistance produced by a wider tire.
However, at one bar you’ll also get pretty significant sidewall bulging—not a problem in pure sand, but a very real one if that sand hides the vicious limestone outcroppings the Egyptians call kharafish. In such terrain you have a choice: flotation or sidewall protection?
We faced that choice in Egypt early this year, when we took three Land Cruisers up the Dakhla Escarpment, a 1,000-foot cliff only (sometimes) negotiable by vehicle because the Abu Moharek dune chain—the longest in the world—spills millions of tons of sand over the edge, forming a loose and shifting series of ramps. The climb intersperses sand and limestone with such unpredictable frequency that there’s simply no possibility of airing down, then back up, then down.
Given the very real specter of seriously damaging several tires, we let a few token pounds out of each corner. Then, with 1HZ diesels roaring, we took turns tackling each section of sand ramp, sometimes succeeding, sometimes churning slowly to a halt before backing down to try again. On one section I got off line and slid in ignominious and hilarious slow motion off the crest and into a trough. Only the steepness of the terrain enabled me to back down without assistance to make another attempt.
In a couple of hours we’d gained the top of the escarpment, with the loss of just one tire against a cunningly buried razor edge. Once through another, flatter section of kharafish, the terrain smoothed out into more homogeneous sand flats and dunes. Time to air down properly? Apparently not—Mahmoud and Tarek simply took off at speed, counting on momentum to keep the tires on the surface. I followed, and we enjoyed several minutes of proper LRDG stuff.
However, very soon another local desert term popped up. “Habat” is the word for “soft pools of sand” that merge imperceptibly with the surrounding firmer sand. Mahmoud found one, and in a heartbeat his vehicle was immobile and buried to the axles. Tarek and I circled away and parked, then we all walked over to help.
In general we’d been delighted with the Troopies we’d rented from a local outfitter. They were impeccably maintained and equipped with two spare tires each. However, the sum total of recovery aids comprised a single shovel and a stack of heavy-duty red carpet rectangles, like those you buy at Home Depot as door mats. I’d looked askance at them in Cairo, and now watched with interest as Mahmoud, after we’d excavated around the tires, stuffed one in front of each. He climbed into the driver’s seat, added a bit of throttle, gently released the clutch—and with flawless synchronicity each section of carpet was sucked under its respective tire and spit out the back. Total forward movement of the vehicle: precisely two inches. It was like Land Cruiser moonwalking—the abrupt shifting of four red rugs from the front to the back of the tires gave the visual impression of forward travel. But it was an illusion.
Another trial resulted in another two inches of movement, and some Arabic terms from Mahmoud which I don’t think referred directly to sand conditions. But by this time Tarek had pulled his Land Cruiser to the edge of the firm rhamla (sand); we hooked up the tow rope and slowly eased Mahmoud back to solid footing.
In those conditions, I learned, tire pressure really makes no difference—hit a habat going too slowly and you’re going down. The only defense is momentum and the fact that, blessedly, habats seem to generally be only a few yards across. We successfully made it across dozens more that trip, and got mildly stuck in a few. But we never bothered pulling out the door mats again.
Moral: Those conspicuously shiny perforated aluminum sand mats you see bolted conspicuously to the roof racks of Discos and Land Cruisers parked at Starbucks really do have their place. Effective sand recovery requires a rigid ramp to let the vehicle power its way out of the trough.
Besides, carpet squares bolted in the same spot would look really lame . . .
Aluminum sand mats, or PAP (for perforated aluminum plate)—frequently called sand ladders although not really the same—are available from a number of suppliers such as OKoffroad. A less expensive and very effective substitute (lacking only the stylish Camel Trophy appearance) is the plastic MaxTrax, available from Outback Proven.
For more videos of driving in Egypt, including a completed Egypt Overland promo, go to: https://vimeo.com/conserventures/videos