Sport-touring tires are a unique engineering challenge because by design—or at least in concept—they must be nearly everything to almost everyone. Nowhere was this more evident than at the launch for the new Dunlop Sportmax Roadsmart II, held in early December in Westlake Village, California. Press motorcycles fitted with the replacement for the original Roadsmart ranged from high-revving middleweight racer-replicas to full-blown touring models pushing 800 pounds.
Wait a second, is Dunlop suggesting that you can run the same tires on, say, a Suzuki GSX-R600 as you would on a BMW K1600GTL?
In a word, yes.
“The original Roadsmart was focused to work really well in the wet, get good mileage and handle well,” said Dunlop Product & Marketing Manager Mike Manning. “With the Roadsmart II, we expanded those characteristics. But we also focused on linearity of feel at pretty moderate lean angles—up to 25 or 26 degrees—and more grip as you lean over farther. So, we wanted to give sport-tire characteristics but keep the sport-touring necessity of working well in the wet and having good longevity.
“We’ve noticed a trend that, as long as they get adequate handling and they’re able to use the bike the way they want to, sportbike riders are more apt to put on sport-touring tires to get a little more life out of their tires. It really gets down to how you use the tire.”
Examples of both the GSX-R and the K1600GTL were on hand at the launch, along with a selection of other late-model sporty streetbikes. Over the course of a day, on a winding route that took our group of writers through small towns, on busy freeways and across some of the best two-lane twisties that Southern California has to offer, I rode five different machines: the aforementioned Gixxer, a Honda NT700V, a Honda VFR1200F and two Yamahas—an FJR1300 and an FZ-1.
Ambient temperature prior to the start of the ride was chilly; in fact, I could see my own breath. The previous evening, Joe Rosen, president and CEO of Goodyear Dunlop Tires, N.A., had joked, “Man, I’m freezing my ass off, and I’m from Buffalo!”
Quick warm-up was not one of the subjects that Tire Development Engineer Shawn Bell specifically addressed in his portion of the Roadsmart II presentation. Rather, he focused on more general areas of the creative process—profile, construction, pattern and compound—and how a change made to one area could influence one or more other areas.
“It was a challenge to develop a successor to the Roadsmart,” admitted Bell. “We had to optimize the tread pattern when we changed the profile, and we had to optimize the profile when we looked at silica compound. For one product line to carry the differences in loads is pretty amazing.”
Bell worked closely with Senior Development Rider Rich Conicelli. “We’re constantly calling each other, sending e-mails,” said Bell. “Test rider feedback is very important for me.”
Test bikes at Dunlop’s Huntsville, Alabama, proving grounds are fitted with data acquisition. “We can measure lean angles, wheel slip, wheel spin, acceleration, braking,” said Bell. “But at the end of the day, the most important information that comes back to me comes from the test rider.”
Conicelli says his most important job is to be consistent. He begins every test session on a control tire—a baseline. “If I weren’t consistent,” he said, “we wouldn’t be able to build the tires that we build.”
Intuitive Response Profile technology derived from Dunlop’s pure racing tires uses a steep “tread drop”—the height measured between the tread center and the shoulder edge—to put down a surprisingly large footprint at deep lean angles. Flex Steel Jointless Belt construction is said to improve warm-up and reduce tire growth at speed, further stabilizing the contact patch.
The front Roadsmart II still incorporates Dunlop’s cosecant-curve groove pattern, but the shape, placement and number of those grooves are different to promote more even wear, reduce squirm, extend tire life and increase water dispersion. Even more obvious are the changes to the rear tread pattern. “Not allowing the grooves to cross the centerline of the tire increases stiffness,” said Bell. “That’s one of the ways we were able to improve mileage.”
The tires that we sampled were made in France and Japan, not at Dunlop’s recently upgraded New York plant. “Initial sales in the U.S. will be those tires” said Manning. “The main sizes—120/70-17 front and 180/55-17 and 190/50-17 rears—will be manufactured in the U.S. next spring. It’s the same global-spec tire: same profile, pattern, compound, construction. They’ll be sold side-by-side. Pricing will be very similar to Roadsmart, with just a slight increase.”
On the road, warm-up is quick, turn-in light-effort. When I mentioned the excellent small-bump absorption to Conicelli, his eyes lit up. “I’m glad you noticed that,” he beamed. Mid-corner and high-speed (at times, very high speed) stability are top-tier, as well. Furthermore, the tire doesn’t want to fall into corners or stand up while braking. Even when trail braking on different machines, I was able to continue steering into the corner without exerting additional muscle. IRP works.
Unfortunately, our wet-weather testing will have to wait for another day. Conicelli thinks the performance is going to be a lot higher than most consumers will expect.
“As a test rider, there are certain times when you’re actually blown away,” he said. “The original Roadsmart was very good in the wet, but the Roadsmart II has unbelievable side grip in the wet.
“But I’m just like every other motorcycle rider: I always want more. I’m looking forward to the future, when you can drag your elbow around a wet corner and still get 6000 miles out of a tire.”