Reviewer's Notebook: Bridgestone's NEW Dueler M/T with UNI-T

Nov. 01, 2005 By Dr. Sean Michael

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Bridgestone's new Dueler M/T looks great on Project WomBAT. There's a host of tire technology advancements visible in this picture, and even more that aren't visible.

The Next Revolution in Tires

Truly new tire designs are rare in the modern market. Most companies staked their territory years ago and seem content to retain their respective shares of the market.

The off-road tire market contains three major subgroups -- all-terrain, mud-terrain, swamper/bogger. Some tires excel in one performance area, such as traction, only to sacrifice another area, such as wear or noise level. Offerings in the swamper/bogger market are generally understood to make the sacrifices in the name of maximum trail performance. All-terrain tires (ATs) tend to exhibit much better street handling characteristics, working well on slick rock and packed snow and dirt. Mud-terrain tires (MTs) fall somewhere in between, handling all but the most severe muck, but can be noisy enough to try the patience of all but the most forgiving spouses.

BFGoodrich has long ruled both AT and MT categories, virtually uncontested. One of their main competitors, Bridgestone, produced solid entries in both MT and AT markets for years. When Bridgestone and Firestone combined forces in 1990, their mutual strengths aligned and focused first on track and street tires, and now on off-road tires as well. With the release of the new Dueler A/T and M/T, both with the revolutionary UNI-T® technologies, Bridgestone has thrown down the gauntlet.

Bridgestone's UNI-T (Ultimate Network of Intelligent Tire) technologies are supercomputer-generated to determine the ideal shape for different tire applications, modeling ride comfort, noise generation, fuel efficiency, tread life, and handling on wet and dry pavement and on off-road conditions.

CO-CS® (Computer Optimized-Component System) yielded a distinctive chiseled M/T shape. The obese sidewall bulge seen in so many other tires is absent; it only serves to increase the tire area that must break through a surface but offers no additional grip. Bridgestone also placed a raised rubber strip, approximately 1/8" tall and 1" wide, at the apex of the sidewall. Present only on the blackwall side, this strip is innovative armor against rocks and roots.

There is also a peculiar thickness in the 1/2" or so just off the rim. Yet another Bridgestone innovation, the Rim Guard is a tough raised rubber ridge just off the rim. This protective barrier prevents impact or low running pressures from compressing the sidewall and pinching it against the rim. Rim Guard protects the tire from pavement edges and curbs, and offers obvious benefits to the rocks and roots that come with serious trail travel.

To address tire form integrity, O-Bead® produces a rounder tire shape by using a bead cable design with a single, continuous strand rather than an overlapped joint. For road use, this translates into improved handling. For off-road use, the benefits stem from the more precise fit between the rim and tire. This tighter bead resists bead separation -- even the fella mounting the tires remarked at how tight the fit was and what strength the bead had.

Bridgestone's Spiral Wrap? technology places a continuous nylon strip along the tire's shoulders. This also helps ensure tire shape uniformity, improving handling and ride quality.

The least obvious technology implemented in the Duelers may be the rubber from which the tires are made. L.L. Carbon® relies upon a switch from carbon black, the traditional reinforcing material that has cluster-like molecular structures, to long link (L.L.) Carbon. Bridgestone reports that L.L. Carbon® enhances resistance to strand failure, increasing wear-resistance, and decreasing chipping, cracking, and tearing, as well as improved grip in wet conditions.

5? Noise Reduction®, the final technological advance in Bridgestone's tires is also invisible to the eye. Four wheelers often accept that mud terrain tires grippy enough for good trail performance also must be annoyingly loud. Bridgestone's engineers disagreed, and optimized tread block element locations to create noise-canceling sounds waves. Bridgestone reports that the aggressive mud-terrain Duelers sounds more like an all-terrain tire.

UNI-T®? What's that?

Close inspection of the new M/T reveals a host of small differences from other tires. This tire is standard in that it is round and black, but the shape has plenty of interesting details....

The aggressive sidewall tread blocks extend down the sidewall, increasing the tire's grip and protecting its shoulder. The tires have more vertical sidewalls, with less 'radial bulge' than normal. There's raised rubber ridges near the rim and also at the convex of the sidewall, and the rubber itself seems somehow different to the touch. All these things result from Bridgestone's UNI-T® (Ultimate Network of Intelligent Tire) technologies: CO-CS®, Rim Guard, O-Bead®, Spiral Wrap?, L.L. Carbon®, and 5? Noise Reduction®.

"The Next Revolution in?" Off-road Tires

Every tire in the world reflects its producer's choice of performance priorities. A Formula 1 tire meets very different performance criteria than does an 80,000-mile passenger tire. Formula 1 and passenger car tires represent extremes of the automobile tire spectrums; each balancing factors such as wet and dry surface adhesion, weight, cost, longevity, noise level, etc. The mud terrain tire design is a similar balance of extremes, combining high performance off-road with on-road driveability. Even within this relatively narrow segment of the tire market, competing tires vary greatly.

Many mud-terrain tires are little better on the street than swampers. Their open tread and large lugs, arranged according to a low-tech design, produce an amazing howl. That same low-tech design often provides lousy street handling characteristics, and also limits stopping and cornering capabilities. Poor rubber quality combines with tread design to shorten the lives of such tires.

Other MT tires look aggressive, sporting big lugs and tough names, but reveal shortcomings when taken on the trail: poor self-cleaning, inadequate carcass strength, and dramatic variations in rubber performance at different temperatures. Smaller companies can emulate the look of a given high performance tire, but the design components that yield most of a tire's potential often escape visual inspection.

The new Duelers are most impressive because of the depth of their engineered design, as well as how well they do both on and off the trail. This is big news, because more folks would opt for MTs if they didn't require a big sacrifice in street handling characteristics. More often than not, practicality wins out, and AT designs get the nod. Bridgestone's Dueler M/T, thanks to UNI-T®, sets a new benchmark for duality (or is that Duelality?) of performance.

Testing the Duelers on Project WomBAT

We wanted to test these "revolutionary" changes ourselves, so we mounted a set of 32x11.50x15R Bridgestones M/Ts on Project WomBAT's 8" wide rims with 4" of offset. Even taking delivery of these heavy tires, we knew they weren't flimsy poseur products. The Dueler is substantially heavier than a 33x12.50 Dunlop Mud Rover is. Weight in and of itself is not good, but these tires' mass hinted at what lay beneath all that rubber.

These massive meats increased the levaerage on the Trooper's steering components and easily overwhelmed the tired stock steering stabilizer. We installed CALMINI's steering stabilizer to help damp the jolts and steering oddities created by these larger tires.

Trail Performance

The Dueler is a full-blown mud-terrain tire. Its block-to-void ratio is similar to that of most competing tires. Tread depth for 32" and 33" Duelers is a full 5/8" and the tread blocks and sidewalls provide proven combinations of alternating scallops and mini blocks. Our 32" tires measured 31.8" in diameter.

These tires work! We ran them through changing trail surfaces as fall merged to winter, logging over two thousand miles of Idaho highways, backroads, and trails. Before the rains arrived the Duelers performed flawlessly on dirt and mixed rock. Bridgestone's L.L. Carbon® rubber is a supple, even soft, compound that still exhibits great durability. Despite the open differential- induced wheelspin, 'wheeling through volcanic rock quarries hardly left a nick or a chip in the lugs. The Duelers' stickiness is equally impressive; the tires adhered excellently on both wet and dry rocks.

Bridgestone's Dueler M/T worked equally well in mud and snow, sharp rocks, and wet ice.

When North Central Idaho's seasonal rains swept in, the landscape made its usual pre-frost transformation to slop and stew (too thick to be soup). Here again the Dueler M/Ts revealed their design strength. These tires lack the cleaning capabilities of swampers but handle muck well. I frequently found myself exploring situations in 2WD, surprised at how far just two Bridgestones could take me. The excellent grip in wet muck left me looking for steeper and deeper trails to tackle.

The Duelers proved their prowess yet again when snow fell. The bi-directional tread gripped well in a range of temperatures. While a good winch and a Pull Pal provide the confidence for solo after-work exploring (it gets pitch dark here by 4pm), the Duelers added a lot more. The WomBAT negotiated challenging-looking fields and slopes with minimal incident, thanks to the tires' resistance to breaking free in the snow and mud. The rubber compound remains supple and grippy at freezing and even lower temperatures. While we haven't had the deep snows of January and February yet, we look forward to trying the Dueler in them and reporting back with updates.

The Dueler's bi-directional tread gripped well even in below-freezing temperatures; allowing confidence in mud, snow, ice, or even a mix of all three.

On the Street

The Dueler M/T's well-mannered street characteristics are surprising. The good handling and quiet mannerisms seem in direct opposition to the M/T rating stamped on their sidewalls. Their adhesion was put to the test when running repeated 60-0mph tests with Power Stop's cross-drilled rotors and Metal Master pads. In spite of multiple runs in a light drizzle, stopping distances were virtually unaffected by the slick asphalt (see brake test results). Cornering characteristics are also very good, with good tracking and minimal tire deformation. This is better than we expected with our 8" rims, the minimum recommended for the 32"x11.50".

The most noticeable trait, initially, of the Dueler's street behavior is their well-muted sound level. Bridgestone has really raised the mark in this area; the M/T's slight hum sounds more like an AT than an aggressively patterned mud tire. Switching from BFG ATs to the Duelers caused no complaints from my wife, the commander-in-chief, nor did she file any executive orders after I mentioned that they "should" be louder. Windows up or windows down, the 5? Noise Reduction® technology does its job, and then some.

To date, our only negative (but not surprising) experience with the Duelers was on packed snow. With snowball-quality white stuff packed down to form a hard, slick surface, the Duelers slipped. Thoroughly siped AT tires are markedly better in this kind of road conditions. The big lugs of a MT tire, like the Dueler, need something to bite into. Steering into rough unpacked snow afforded more traction, allowing the Dueler's deep lugs to dig in.

Conclusion

Bridgestone scores big with its new Dueler M/T. Its many and varied advances will cause renewed competition in the off-road performance tire market. In one bold move, Bridgestone showed that a top quality mud-terrain tire could be utterly driveable on the street. With such a short-term test, the verdict is still out on the tire's longevity, but the AT's 50,000-mile treadwear warranty and the lack of wear so far bodes well for the future. Furthermore, with Bridgestone's 30-day test trial satisfaction guarantee, trying a set isn't a risky proposition. With competitive pricing that undercuts the current "king of the hill," you may be looking at the heir apparent to the throne.

Click here to see a table of sizes for Dueler M/Ts available at the time of publication.