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Bfgoodrich Mud-Terrain T/A Km2 Tires - Tire Test

Posted in How To: Wheels Tires on November 1, 2007 Comment (0)
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Photographers: Courtesy BFGoodrich Tires
Our brief mud-pit test was no challenge at all for the new Mud-Terrain, which delivered excellent traction in the goo while self-cleaning quite well despite a relative lack of siping on the tread blocks.

The tread may be brand-new (sort of-astute readers have called it a "mini Krawler" with narrower voids), but the technology underneath it isn't ... at least not entirely. BFGoodrich has retained its time-proven TriGard construction for its newest Mud-Terrain T/A, incorporating three polyester belts in the tread and sidewall, fortified by two each of nylon and steel in the tread. What's new is that the Mud-Terrain now borrows elements of the Krawler T/A's KrawlTek design too: The poly cords are now thicker, some 30 percent over the previous tire's, while a new sidewall compound is said to be more nick- and cut-resistant. It all sounded good to us, and we loved the look and design of the new tire, but we naturally also wondered if perhaps the engineers at BFGoodrich hadn't designed a tread that might be a bit too hard-core (read: noisy and knobby) for the daily-driver crowd. So we hit the road to find out.

Our test rig was a bone-stock JK Wrangler Rubicon shod with a set of 285/70R17 Mud-Terrains, a virtual swap-in for the OE Mud-Terrains that come standard with the '07 Rubicon package. Once on the pavement, we were taken aback immediately at how quiet the new BFG was-far more so than its tread design would suggest. True, the more aggressive tread pattern-and those macho sidewall lugs in particular-resulted in somewhat rougher ride and handling at lower speeds, but road feel smoothed out rapidly as speeds increased, and at 60mph highway cruise, the new Mud-Terrain seemed only marginally louder, and not at all bumpier, than the OE mudders on our in-house JK Rubicon test rig. Overall cornering and lateral stability, while obviously not of Trail T/A caliber, struck us as darn near identical to the previous mud tire's-a stiffer sidewall helping to compensate for a less adhesive tread pattern, perhaps-and given this brand's history of commendable longevity, we'd guess the typical Mud-Terrain buyer will be perfectly content with the oh-so-slight trade-off in pavement performance over the older M-T-especially once he leaves the asphalt behind.

The sidewall of the new M-T may be a bit stiffer than the old tire's, but at 15 psi, the new Mud-Terrain still provides ample sidewall flex for conforming to rocks. The tread's Z-shaped longitudinal pattern lends grip from a variety of angles, and those aggressive shoulder lugs deliver an extra measure of bite at trail pressures.

Airing down to 15 psi, we turned off pavement and headed into the mountains of the Wasatch-Cache region near Salt Lake City for a leisurely half-day of low-range 'wheeling. At lower elevations, the trail was littered with rock gardens-big boulders washed downhill by winter rains-along with intermittent patches of exposed bedrock. Here, the Mud-Terrain's rockcrawling heritage came to the fore, as the deep sidewall lugs and Z-shaped longitudinal voids-the "Linear Flex Zone," in Goodrich-speak-provided multiple biting edges at a variety of angles, and the sidewall itself, while perhaps slightly stiffer than the previous M-Ts, still showed ample flex over rocks at our judicious trail pressures. As the trail rose in elevation, we found ourselves confronted by a number of slow, steep hillclimbs over irregular surfaces, and the new M-Ts likewise handled them with aplomb.

Later in the day, at a hub-deep mud pit, the BFGs likewise didn't work up much of a sweat (or a spin, we should add), churning effortlessly through the claylike goo in spite of our best attempts to clog up the voids. Despite a near-total lack of siping-at least on the outer tread blocks, where you'd normally expect to find it-the Mud-Terrain does sport small lateral side channels inside the outer voids themselves (they look almost custom-grooved). These ridge-like channels must be there to help the tire self-clean more readily, because self-clean it readily does.

Lurking beneath the 20/32-inch tread, BFG's newest Mud-Terrain T/A utilizes three plies of polyester and two reinforcements each of nylon and steel. As you might guess, the new tread is a bit bumpier at slower road speeds than the old version, but it smooths out quickly as speeds increase, and the stiffer sidewall helps compensate for a more open tread design on the highway.

The only surfaces where the new BFGoodrich didn't excel were extremely loose dirt and dusty silt beds at higher-than-normal speeds-prerunner stuff, in other words. Here, the treads tended to dig, and keep digging, straight into the talc rather than float over it, resulting in some less-than-stellar directional stability under sharp steering at higher speeds. It's not that the new BFGs couldn't perform better in the soft stuff, and a more experienced (i.e., race) driver would have likely achieved better results with them than we did. Suffice to say, though, that the KM2 wasn't really designed with Baja running as its primary application. Then again, we already have the very capable (and competition-proven) Baja T/A in the BFG stable for that very purpose, so the performance "loss" is no biggie here.

While it's obviously inspired by rockcrawling, and built with purpose-built trail machines in mind, owners of fullsize and/or tow rigs who are interested in improving their trucks' performance in the dirt, or who simply want a more macho-looking stance, could likely benefit from the KM2s as well. Load capacity approaches a hefty 3,200 pounds at 65 max psi, so just about any light-duty truck could run these treads, even at full payload. Bottom line, the new BFGs are win-win rubber to our minds, a superior rock tire that also excels in mud while still retaining perfectly respectable street manners.

Well, yes, so here's the bad news. OK, it's only partly bad, as any tire that performs as well as the KM2 is a welcome addition to the 4x4 tire market, but for those of you who are wedded to your 15-inch rims, you'll need to wait awhile longer to try on a set; BFG's first 16 sizes of the Mud-Terrain, available now and ranging from 31 to 40 inches tall, are only available in 17-inch-and-higher rim diameters (with one exception, an LT315 for 16-inchers). Fear not, though-by September '08, BFG will have rolled out 18 additional sizes for 15s and 16s, including most popular trail sizes up to a 35x12.50R15. And now that we think of it, it's all good news-because the way we see it, a tire this good is definitely worth the wait.

Tire: BFGoodrich Mud-Terrain T/A KM2
Size: LT285/70R17
Type: Radial
Load range: D
Max load (lb @ psi): 3,195 @ 65
Sidewall: Three-ply polyester
Tread: Three-ply polyester, two-ply steel, two-ply nylon
Approved rim width (in): 8.5-11
Tread depth (in): 20/32
Tread width (in): 9.0
Section width (in): 12.2
Overall diameter (in): 32.6
Static loaded radius (in): N/A
Revolutions per mile: 634
Weight (lb): N/A
Test vehicle: 4,100-pound Jeep Wrangler Rubicon

Sources

BFGoodrich
877-788-8899
www.bfgoodrichtires.com

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