With two Discoverys and a...
With two Discoverys and a Range Rover, Hankook set out to prove that its Dynapro ATm tire compares favorably with the Toyo Open Country A/T and the venerable BFG All-Terrain T/A, using trails around Big Bear, California, as testing grounds. In the foreground is the Toyo-equipped white Land Rover, followed by the "emergency-Rover" on Hankook tires, and then the green Land Rover with BFGs.
Perhaps our whining from last year's introduction of the Dynapro ATm had an influence, as we questioned the possibility of fairly evaluating a new tire with three unknown factors; the trails, the vehicle, and the tire. Or, it could very well be as simple as Hankook wanting to show how the RF10 compares to a top-notch all-terrain and a benchmark A/T that everybody is familiar with. Either way, Hankook did stick its neck out when offering journalists the chance to drive three very similarly equipped Land Rovers with same-size tires over a variety of trails, obstacles, and test areas.
Of course, few things that require lots of planning ever go as intended, and this event was no exception. The plan was to have the three sets of LT265/75R16 tires on the aforementioned Land Rovers, but one...well, ahem...blew up on the way to the 6,750-foot elevation of Big Bear, California, after losing its water pump. Whitworth-savvy master mechanic Malcolm Buckeridge quickly readied a Range Rover as a stand-in, and since the chassis is the same as a Discovery's, we see no real reason why the outcome of the test would've been any different had the one Land Rover not croaked. Otherwise, no British vehicles were harmed during this testing.
A Fair Comparison?
We were assured that the vehicles were of roughly the same weight, on 7-inch-wide rims, and all equipped with Old Man Emu medium-duty 11/2-inch suspension, but the Hankook-shod ersatz Rover had very cushy Pro Comp shocks while the other two ran far stiffer Koni Heavy Track RAID dampers. Did this influence the test in any way? Probably not, at least not enough to make a difference that we could notice-and we sure tried to. But speaking of differences, one look at the spec charts will tell you that two of the tires are very, very similar in both size and construction; the BFG is also really close as far as the size goes, except for the tread width, and with a slightly different construction. This turned out to be quite noticeable in a few circumstances.
Most obvious, the BFG looks like, well, a BFG All-Terrain, while the Hankook and Toyo tires may be virtually indistinguishable at a distance to the casual observer. We won't dwell on who inspired who here, but the Open Country A/T has been around for a while. And it's a darn good design to mimic if you want a tire that handles both street and trail use.
 Don Alexander, our trail guide...  Don Alexander, our trail guide and organizer, had put together a good variety of trails and other obstacles that pushed both the tires and vehicles to their limits. Sometimes we made it over an obstacle, other times not. This happens to be a "not" moment, with former Four Wheeler editor Mark Williams piloting the Dynapros along a line that none of the tires could master. |  Part of a short test loop,...  Part of a short test loop, this hill had the Rovers stretching their flexy Old Man Emu suspensions to the limit. Right to the limit, meaning that the tires had their work cut out for them, and that locking the center diff made a difference. While we had several ties, this was one place where the BFGs came out ahead, and noticeably so. |  All three sets of tires had...  All three sets of tires had been subjected to harsh testing for four months prior to this particular jaunt, which included slalom courses and other pavement punishment. Two of them (a BFG and a Hankook) already had nasty cuts in the bead area-and the rim damage to complement it-but here it's a Toyo that gets squeezed. Pretty darn flexible for a load-range E tire at 12.5 psi. |
Oddly enough, when we checked the durometer (hardness) readings of the treads and sidewalls, all three had identical readings of 62 and 52, respectively. It should also be noted that these sets had been used for somewhat brutal skidpad testing and other hard pavement use-some 3,500 miles' worth, plus a fair amount of trail driving-before the tests we attended even began. So they were indeed broken in. Two of them also nearly broken, sporting some deep sidewall cuts. This, we concluded, was due to driver error and not tire-related as the rims had dented from the impact, indicating excessive speed combined with bad judgment.
OK, so it may not have been a perfect apple-to-apple comparison, but it's still the best tire versus tire comparison put on by a manufacturer that we've ever witnessed.
There were a few instances...
There were a few instances where it became obvious that the tires didn't have nearly as much to do with forward progress as did picking the correct line. Sometimes adjusting 1/2 inch to the side made all the difference, and while we didn't necessarily learn anything more about the tires in those places, it was fun four-wheeling.
Telling Them Apart
Getting the numbers for the spec sheets turned out to be the hardest and most time-consuming part of compiling this story. It would've been really easy to simply state that the Hankook and Toyo tires usually performed about the same, while the BFGoodrich T/As generally did differently-sometimes better, sometimes worse. While it's fairly obvious why the BFG's wider tread worked better in soft sand, for example, there were so many close calls that we wanted to have all the specs in order to better understand the tires' behavior, and to enable explaining it to our readers.
Although we eventually got all the numbers for spec sheets, there are errors. For example, there's no way that the RF10's Revolutions Per Mile figure combined with its Static Loaded Radius (653 RPM and 14.7 inches) can be matched with the Toyo's 659 RPM and 14.1-inch SLR-not when both are listed as 31.7 inches tall. Somebody's off the mark by quite a bit here-we just don't know for sure who, or where-but simple math disagrees with the numbers we were given. Why does this matter? Well, when two tires are so close in performance, it would have been nice to know if one tire's traction might have been better because of a longer contact patch (a lower SLR), or perhaps because a smaller footprint created higher contact pressure.