DUNLOP N-Tec REAR TIRES
ROAD RACING TIRES
Dunlop's NT construction features a carcass design that improves tire compound performance across a broad range of conditions—so much so that it has dominated competition in the AMA Superbike Series, taking every championship possible since its introduction in 2004. “Not only does the NT provide consistent and predictable handling from the start,” said Dunlop Road Race Manager Jim Allen, “it's also common for a rider using an NT to run his fastest lap late in the race.”
The multi-compound NT tires will be offered in three variations: soft, medium and hard. “These are the same multi-compound NT rear tires that our factory and support riders have used throughout the 2006 season,” said Allen. “We now have the capacity to offer them to racers in all of the classes in 2007—Superbike, Superstock, Supersport and Formula Xtreme.”
Dunlop has so much confidence in its compounding and construction capability that the company willingly discusses the attributes of the world's premier road-racing tire. Carcass construction varies depending on the racing class, the particular track and the anticipated temperatures. For example, a nylon carcass ply inclined at approximately 90 degrees to the circumference of the tire may be overlaid with two nylon breaker belts followed by a continuously wound, aramid-fiber tread belt. The angle of the breaker belts to the carcass ply and to each other can be varied to alter sidewall stiffness and the all-important “feel” that the rider experiences in transitions. Materials may differ as well, both for the reasons stated above and for their ability to withstand heat and stress. They include rayon, polyester (polyethylene terephthalate, or PET, and polyethylene naphthalate, or PEN) and polyolefin (polyolefin ketone, or POK).
Multi-compound tread is a signature feature of the N-Tec. Dunlop's considerable expertise in compounding, development and testing is a key reason why the NT tire has been accepted so rapidly by the AMA's factory teams. “We typically put three compounds together on our N-Tec tires,” says Watkins. “This allows us to offer the ideal combination of traction for any given track. We can tune the center traction compound for high speed, and the left and right lateral-grip compounds for anticipated cornering loads.”
The physical process of mating the three compounds to each other and to the carcass is extremely crucial to the feel and feedback the rider experiences. “You can have the proper design--carcass, materials and compounds--but unless you can consistently duplicate the construction methodology in a manufacturing environment, it's not worth much,” says Watkins. “We hold several patents in this regard, and we have a very sophisticated machine that allows us to ‘tune' each and every tire. For example, we can stiffen or soften the sidewall and vary the compounds all at once, following a complex template that factors in our development and testing knowledge.”
Since slick tires are not allowed for Supersport competition, Dunlop manufactures molded Sportmax GP tires using the N-Tec casing principle in a treaded tire. FEA (finite element analysis), first applied by Dunlop on the D207, produces a cosecant-curve design where the tread grooves continuously coincide with the forces running through the tire. As the curving tread pattern travels across the tire to the shoulder area, it keeps the driving and braking forces aligned properly as cornering forces come into play. Like the earlier Sportmax GP, the molded N-Tec Sportmax GP has enhanced longitudinal elements in the center of the tread for improved wet-surface grip.
Dunlop's first priority with N-Tec testing was the AMA Superbike class, followed soon after by Superstock. Both classes feature 1000cc machines capable of speeds between 180-200 mph, velocities that strain the limits of the best traditional designs available.
“We first started testing the NT late in the 2003 AMA season,” says Dunlop Road Racing Manager Jim Allen. “Beginning in 2004, we started receiving them in larger quantities, and this sped up our testing considerably.”
What feedback did the riders provide? “They immediately noticed that straight-line stability was much better, and of course this made setup easier for the technicians because the teams did not have to juggle sprocket sizes to accommodate tire growth. At the same time, riders also noted a completely different feel when entering turns, and some of them were uncomfortable with it.”
Specifically, the early N-Tec designs occasionally gave the feeling that the tire was moving or sliding as the rider tipped the bike into a turn. This introduced an element of doubt about available traction.
“It's safe to say our initial testing focused on solving that problem,” recalls Allen. “We kept raising tire pressure, but the result was counterintuitive. We found that lower pressures worked better and had the added benefit of providing a much bigger contact patch on turn exits. That gave the tire more traction and better bump absorption, which translated to better exit traction.”
Indeed, the inherent structural integrity of the continuously wound NT carcass “protected” the compounds from heat buildup, which in turn allowed the R&D engineers to experiment with softer compounds than they had initially anticipated.
Allen's test engineers then discovered another valuable tidbit: While softer lateral-grip compounds worked very well on the N-Tec, there was no measurable benefit from using higher-grip traction compounds in the center of the tread. The ever-increasing power of the Superbike and Superstock bikes readily spun the rear tire even at speed--imagine a rear tire turning 15-20 mph faster than a Superbike's terminal velocity on the high-speed Daytona banking. So the logical conclusion was to utilize compounds that could withstand the constant abuse and maintain consistent lap times.
• Softer feel in corner entry.
• Remarkable consistency in lap times over the life of the tire; fastest race laps are commonly achieved in the last few
laps of long races.
• Significant increase in corner exit grip.
• Significant increase in directional and high-speed stability.
• Wide range of acceptable suspension settings.
Dunlop’s new generation of rear tires for 2007, the N-Tec series, represents a significant departure from our former
methods of rear tire casing construction.
available in both Slick and DOT-approved versions.
Dunlop N-Tec rear tires have the N-Tec designation clearly displayed in the sidewall stencil which appears on the
LH sidewall of N-Tec rear tires.
Non-N-Tec Dunlop rear tires do not carry the N-Tec logo on their sidewalls.
SUGGESTED PRESSURES - Set N-Tec rear tire pressures HOT just after you remove tire warmers.
DAYTONA - 28 psi HOT - If tire warmers are not used, suggested tire pressure is 26 psi Cold
ALL OTHER TRACKS - 23 psi HOT - If tire warmers are not used, suggested tire pressure is 21 psi Cold
Due to the new N-Tec design, tire pressures are alot lower than NON NTECs.
GEARING - Rear N-Tec rear tires do not grow at speeds, try gearing down one tooth on the rear sprocket.
NO CHANGES are needed to the following: RIDE HEIGHT