Bridgestone Adventure and Sport Touring Motorcycle Tires Review
Bridgestone’s design objective for its all-new Battlax Adventure A41 and Battlax Sport Touring T31 tires is seemingly simple—increase rider feel and confidence without sacrificing wear and durability.
However, this is proverbially tantamount to having your cake and eating it too, and usually unattainable without some sort of divine intervention or revolutionary technological breakthrough—and the latter is exactly what Bridgestone has developed.
Enter Ultimate Eye. No, it’s not the diabolical arch nemesis from the latest Bond film, but for motorcyclists, it is actually much cooler than that. Ultimate Eye the technological spawn of the Bridgestone R&D team and it efforts in developing tire solutions at the highest echelons of motor racing—MotoGP and Formula 1.
Ultimate Eye is a futuristic proprietary technology that is described as a “laboratory dyno for tires.” It stimulates varying loads and surface conditions, measures stresses and contact properties in real-time, and logs and crunches the terabytes of resulting data to rapidly iterate designs in the quest for the Holy Grail of Grip. Did they succeed?
I traveled to beautiful and exotic Ouarzazate, Morocco to put these new shoes from Bridgestone to the test on the unforgiving and relentless terrain on the northern edge of the Sahara Desert.
To understand how the new Battlax tires perform, it’s important to know how they are built. Both the A41 and T31 take advantage of mono-spiral belt construction; a single strand of steel cord is wrapped lengthwise around the circumference of the tire, eliminating seams and crossed belts. Compared to conventional cross-belt construction, the result of mono-spiral construction is a lighter tire that provides better shock absorption and generates less internal heat.
Dual-compound construction is utilized for the rear Battlax T31, as well as for both front and rear for all sizes of the Battlax A41 (save the 21-inch front tire which is not physically wide enough for the dual-compound approach).
Bridgestone’s 3LC (three-layer compound) is softer and grippier on the shoulders and stiffer around the center of the tire. In this way, the stiffer compound makes up the cap or center section of the tire, as well as the base of the tire carcass. This provides stability across the lean-angle spectrum, regardless of which compound is in contact with the road surface.
The Sport Touring T31 front tire is constructed from a single compound utilizing a new molecular approach to better disperse the silica (think fine sand) throughout the rubber for better grip, flexibility and, ultimately, better rider feedback.
To improve wet weather performance, Bridgestone has increased the sea/land ratio on the shoulder tread of the new Battlax tires, while slightly decreasing it across the center of each tire. The sea/land ratio refers to the amount of rubber versus grooves in the contact patch of the tire.
By increasing the ratio on the shoulders, the new Battlax rubber can evacuate water at a higher rate while turning. Bridgestone’s own internal testing boasts an eight percent improvement in wet weather handling performance for the A41 and three percent better for the T31 when compared to their predecessors, the A40 and T30.
For the Battlax Adventure A41 test, I selected a representative smattering of potent adventure machinery, including a BMW R 1200 GS with modified suspension, the potent KTM 1090 Adventure R, the multi-purpose Honda Africa Twin, and the venerable Triumph 800 XC.
Of the bunch, the BMW is the only one with a 19-inch dual-compound front tire, while the others utilize 21-inch front wheels. For the rear, the KTM and Honda run 18s, while 17s are used on the BMW and Triumph.
The Adventure A41 tire is marketed as a 90/10 tire, meaning 90 percent street and 10 percent dirt. However, our route through the Moroccan desert reveals that tarmac is a relative luxury in this part of the world, and the 200-mile route is a little more like 50/50. Modern traction control and ABS have made off-piste adventuring much more accessible to the masses, which is a good thing, but I switched off both to gain a better feel of the limits of the tires.
On long flowing dirt roads, strewn with imbedded rocks and topped with loose gravel, I was immediately impressed with the ability to steer with the rear tire. Under hard acceleration, the A41 rear would release predictably and then steadily regain traction, allowing me to drift the rear end around sweeping turns.
Late braking on dirt roads can sometimes end up in disaster, but blind turns and stray goats make for a perfect test case. While under heavy braking loads off-road, the A41 front rubber found an amazing level of grip across the dry clay surface, even while tipped sideways, which undoubtedly saved the lives of countless young and oblivious goats.
When the dirt gave way to dusty and pockmarked tarmac, I switched traction control and ABS back on, and increased the pace. Aboard the BMW R 1200 GS, the 19-inch front was absolutely impressive. Turn-in feel was consistent and carving up dirty asphalt has never been so much fun. Again, encountering goats and the occasional donkey cart kept the excitement level pegged, and the performance of the A41 rubber was on point.
It was difficult to match the same pace while piloting one of the bikes with a 21-inch single-compound A41 front tire. Although the 21 works incredibly well off-road with increased roll-over capacity for larger obstacles, on the tarmac, its size works in the opposite direction.
The narrower width and taller profile turns slower and the smaller contact patch provides less camber-thrust, an engineering term used to describe the turning power generated by the lateral forces applied to the tire’s contact patch. Still, for real-world adventure riding, I prefer the off-road advantage afforded by a 21-inch wheel and consider the slower pace on the tarmac a timely opportunity to soak up the local scenery.
After a day of flogging the Battlax A41 across myriad nasty surfaces and temperature ranges, the tires looked fantastic. On the larger bikes, there was some visible wear on the rear—undoubtedly from the embedded sharp angle rocks in the off-road portions of the route—but the tire held up incredibly well.
The Adventure A41 front tires looked to have fared even better and, despite encountering a few big high-speed impacts with rocks, the spoked wheels and tires emerged unscathed.
With the lovely dirt roads behind us, it was time to spend the next day putting the Bridgestone Battlax Sport Touring T31 tire through the wringer. To evaluate the mettle of the T31, I selected one of my favorite sport touring bikes and a notorious annihilator of all things round and rubber—the KTM 1290 Super Duke GT.
Except for a singular stretch of brand new tarmac, I ripped the throttle through dirty, rough and unpredictable tarmac, a virtual baptism by fire for any set of tires. The Sport Touring T31 rear was very stable and assumed the role of silent partner in my relationship with the asphalt.
The T31 did everything I asked of it, both under hard acceleration and full braking, and did so without issue. However, it was the predictable grip and feedback I so tenderly received from the Battlax T31 front tire that I immediately fell in love with.
I spent the balance of the day pulling and creating gaps in traffic so I could attack the tarmac at full speed. The T31 front felt extremely planted and sticky, even across roads that would make Baja California look like the Autobahn. Even the decreasing-radius turns that caught me by surprise were handled with ease, with superb edge-grip while heavy on the brakes.
Bridgestone claims that the contact patch is seven percent larger on the T31 over its predecessor. That equates to more bite and camber-thrust for increased carving power.
With the sun setting and a couple hundred miles beneath my helmet, I was certain that the rapturous time I had carving up the desert tarmac must have been torturous for the tires. Upon inspection, I was surprised to see how well the Battlax Sport Touring T31 tires held up. Absent were gummed up groove edges or any visible signs of extreme wear.
Even without the opportunity to test the new Battlax rubber in wet conditions—it was the Sahara Desert, after all—I came away very impressed. The Bridgestone Adventure A41, despite being a 90/10 tire, performs at 100 percent on both asphalt and dirt roads, and is an obvious choice for all-out adventure riding.
The Bridgestone Sport Touring T31 tire provides high levels of grip across a wide spectrum of less-than-perfect tarmac. The T31 front tire stands apart with incredible feedback and feel, the reciprocal relationship between road rider and road surface that is so highly sought after.
Good on the Bridgestone engineers and their Ultimate Eye secret weapon, and their quest for the Holy Grail of Grip—a mission accomplished.
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Bridgestone Battlax Adventure A41 Review Photo Gallery
Bridgestone Battlax Sport Touring T31 Review Photo Gallery