For 2013, Pirelli is introducing the successor to the Angel ST, the Angel GT, and no, it doesnít make funny faces anymore because, as Pietrangeli put it, ďitís no longer time to be funny.Ē Indeed, the new Angel GT is all business and aims to improve upon the ST in two key areas: wet performance and longer mileage.
Describing the GT as a sport-touring tire isnít entirely accurate. Pirelliís market studies indicate more than 30% of the tires sold in Europe are sport-touring tires, but only 12% of motorcycles on the road are in the sport-touring category. It found that buyers could be separated into three groups: commuters, weekend warriors and long-distance riders. Besides sport-tourers, these groups were also riding nakeds, adventure-tourers and sportbikes.
The task then was to build a tire to suit the needs of these groups. It had to come up to operating temperature quickly and last a long time while maintaining the handling characteristics Pirellis are known for, both in the wet and dry.
Starting with the tread pattern, the GTís design closely mimics the STs but incorporates more continuous grooves for better water evacuation. Groove depth is reduced on the shoulders for better edge grip and increased stiffness. All told, the GT achieves a 10% and 16% greater land/sea ratio front/rear compared to its predecessor.
Because most riders will wear the middle of their tires before the sides, the new tireís curvature is actually slightly flatter in the center but 5% sharper at the edges, compared to the ST. One might think the greater contact patch would accelerate wear, but Pirelli says otherwise. The bigger footprint actually loads the stress more evenly on the tire, which then improves tire life.
To provide the structural support needed for the bigger footprint, the GTís carcass is derived from Pirelliís World Superbike tire. From a compound perspective, the GTís have a high silica content, which is known to come up to operating temperatures much quicker than carbon black used primarily in racing tires and offers enhanced traction in wet conditions.
In fact, silica is main element of the front tire, which contains zero carbon black. The rearís dual-compound design incorporates both materials, with the base and center 20% of the tire made from a 70/30 mixture of silica and carbon black for quick warm up, durability and high feedback.
The remaining 80% comprising the sides and shoulders of the rear tire utilize the same silica compound as the front tire. To combat silicaís natural performance drop off at high temps, Pirelli chemists have come up with reactive resins, hybrid polymers and nanomaterials specifically for the GT to maintain its performance levels while hot.
What this means for the street rider is a tire that comes to temperature very quickly and maintains its performance for much longer than the Angel ST, or any of its competition. More on that later.
Wet Testing Taken To The Extreme
Pirelli is investing heavily in its sport-touring tire and invited the worldís press to Southern Italy to give them a try over a two-day span. And not just any location in Southern Italy, but aboard the flight deck of the countryís flagship aircraft carrier, the Cavour, named after Italyís first post-unification prime minister. Here, journos would perform wet braking drills on the watered-down surface of the flight deck.
Each journo got just three passes down the strip on Kawasaki Ninja 1000s fitted with the Angel GT. Honestly, the wet tests didnít prove much, as Pirelli personnel admitted the flight deck had a much higher coefficient of adhesion ó 0.9 compared to 0.6 on an average road. So even with the wet surface, stopping distances were expectedly short.
This was a rare instance where I think I could have stopped shorter without ABS, as the conditions were tricking the Kawasakiís system to activate, when in fact it wasnít necessary due to the amount of grip available. When tested on average road surfaces, Pirelli asserts the GT consistently stops from 60 kph (36 mph) three meters (roughly ten feet) shorter than the ST.
The second dayís testing was around the handling circuit at the Nardo Ring, the Porsche-owned facility most famous for its eight-mile paved circle viewable from space. While we didnít ride around the circle, the facilityís 3.7-mile road course would be an extreme test of the silica capabilities Pietrangeli explained to us previously. The range of motorcycles included everything from BMW R1200RTs and Yamaha FJR1300s, to Triumph Street Triples, Kawasaki Z800s and even a Yamaha YZF-R1.
Regardless of the bike I rode on this partly cloudy, 64-degree day, the first thing I noticed was how quickly the tires reached operating temperature. Within three corners, knee-dragging confidence is achieved, even on a big touring bike. The flatter profile of the rear center does require the slightest bit of effort to initiate turn-in, but the majority of riders will hardly tell the difference.
Once leaned past the center, the rounded profile feels extremely linear from partial lean to full lean and allows the rider to tip the bike over to the edges smoothly and without worry. Consistent hard braking never upset the front, even while trail-braking. Itís worth noting, however, this is a sport-touring tire and, as such, doesnít have the ultimate levels of grip on the edge as Pirelliís Diablo sport and racing line.
While I was extremely impressed by the Angel GT in these conditions, going out for a session aboard the R1 cemented my impressions of Pirelliís new tire. While clearly not meant to be a race tire, the GT ably handled the punishment dished out from the R1 at both ends. The front tire tracked predictably where it was pointed, and with substantial assistance from the Yamahaís traction control, the rear was still able to provide enough stick to launch the R1 aggressively onto the trackís long front straight.
Whatís more impressive was the visible condition of the tires at the end of a full day of track lapping with 40-odd journalists Ė they hardly showed any signs of wear. Not even rubber marbles or ripples on the edges typically seen after performance riding. Pirelli have clearly developed a winner in the S-T segment with the GT.
Of course, the one parameter we couldnít measure after our relatively brief time with the tire was its durability. For this, Motorrad Test Center, an independent third party, compared the Angel GT against the Michelin Pilot Road 3, Dunlop Sportmax Roadsmart 2, Bridgestone Battlax BT023, Continental Road Attack 2 and Metzeler Roadtec Z8 Interact against each other in a series of handling tests at different mileage intervals. Ultimately, the Angel GT performed best of the bunch in terms of longevity, followed by the Michelin, Bridgestone, Dunlop and Continental. The drop off in performance from the GT proved to be a more linear downward slope compared to the second-place Michelin, which dropped off more dramatically.
An internal wet braking test, not conducted by the Motorrad Test Center, also concluded the Angel GT the best in this category as well, stopping more than a meter (three feet) shorter than its closest rival, and almost four meters (13 feet) shorter than the last place finisher from an undisclosed speed.
The Pirelli Angel GT is a seriously impressive tire for the sport-touring crowd and one to be considered should you be in the market. True to its claims, it handles similarly to the Diablo line of sport tires yet will last significantly longer.
Itís available in popular sizes for both 17-inch and 18-inch wheels. Front tires retail around $195, rears up to $264. Visit www.pirelli.com/moto for more information.