May 9, 2008
There was a point in time when if you wanted an Ultra High Performance Summer tire it had to have a highly directional tread pattern. And while directional tires have a fashionable appearance, function was usually the designer's driving force as they tried to balance the need fora relatively solid tread pattern to achievedry performance goals with the ability to cope with water on the road when driving at highway speed. Directional tread patterns were an easy way to combine both with good result but in most cases proved to bring with it a real world penalty. Tires with highly directional tread patterns often start life being somewhat loud and are more likely to develop some irregular wear during their life, further increasing bothersome tread noise. Their uni-directional tread design limits tire rotation options, limiting the maintenance possibilities to try and minimize irregular wear. While there are currently no noise limit standards in place in North America, Europe has already adopted increasingly tough pass-by noise standards which put pressure on tire engineers to develop quietertires that still deliver the dry and wet performance levels we have come to expect.
We've been seeing a trend away from highly directional tread patterns towards asymmetric designs. These asymmetric tread patterns feature relatively solid outside shoulder blocks to provide plenty of dry cornering traction and resist wear from "spirited" driving while utilizing a more open pattern on the inner half of the tread area to aid wet performance and minimize the chance of hydroplaning at higher speeds. Following this trend, the new Bridgestone's Potenza RE760 Sport features a modern and stylish asymmetric tread pattern, replacing the Potenza RE750 with its traditional directional tread pattern.
To find out how the Bridgestone Potenza RE760 Sport and its asymmetric tread pattern performs, the Tire Rack team conducted a Real World Road Ride and Performance Track Drive, comparing it with some of the most popular tires in the category: the BFGoodrich g-Force Sport T/A KDW 2, Michelin Pilot Exalto PE2 and Yokohama S.drive.Our evaluation used 2008 BMW 325i E90 coupes with new, full tread depth 225/45R17 tires mounted on 17x8.0" wheels.
Our 5.6-mile loop of expressway, state highway and county roads provides a great variety of road conditions that includes city and highway speeds, smooth and coarse concrete, as well as new and patched asphalt. This route allows our team to experience noise comfort, ride quality and everyday handling, just as you would during your drive to school or work.
Out on the road, all four Ultra High Performance Summer tires delivered responsive steering and stable handling. The Michelin Pilot Exalto PE2 felt particularly nice in the handling departmentdisplaying a nice blend of responsiveness and weighted steering feel. The Bridgestone Potenza RE760 Sport was very close behind with just slightly slower initial steering response than the Michelin. The Yokohama S.drive was the most responsive of the group but felt somewhat nervous in comparison to the Michelin or Bridgestone. Rounding out the group was the BFGoodrich g-Force T/A KDW 2 displaying steering response that was slightly slower than the other tires in the test.
Ride quality for the group was found to be firm but not harsh. Of special note was the Pilot Exalto PE2, which offered the best ride quality of the group. This tire did a very good job at minimizing the harshness of the sharper impacts along our route while also controlling the jounce encountered over the rolling and undulating section on the 2-lane country road along our route. Again close behind was the Potenza RE760 Sport, which also did an excellent job coping with the road's irregularities and bumps. The S.drive and g-Force T/A KDW 2 were similar in their overall ride qualities but both were somewhat firmer than the Michelin or Bridgestone over the rougher patched pavement along the route.
The Michelin also produced the least amount of tread pattern or impact noise, rolling along surprisingly quietly for an Ultra High Performance Summer tire. The Bridgestone also generated modest tread noise with just a hint of growl at lower speeds. The Yokohama ranked third overall displaying the traditional hum associated with highly directional tread patterns. Rounding out the group was the BFGoodrich tire. This tire's stylish appearance was a hit with most of our team but once behind the wheel all found it generated an annoying growl at all speeds that even wind and vehicle noise at highway speeds couldn't drown out.
Our 1/3-mile per lap test track course includes 90-degree street corners, lane changes and simulated expressway ramps. Run in both dry and wet conditions, the test track allows our team to experience the traction, responsiveness, handling and drivability normally only encountered during abrupt emergency avoidance maneuvers or competition events.
Out on the test track, all four tires performed very well in dry conditions with less than 0.2 second separating the group. In the end, the Michelin Pilot Exalto PE2 was fastest, able to lap the course just 0.09 second ahead of the Bridgestone Potenza RE760 Sport. While the lap times were very similar, the handling was noticeably different. The Michelin displayed a well-balanced feel with equal grip at the front and rear while the Bridgestone showed gentle understeer when it reached the limit. Our team found the Yokohama S.drive to be very responsive but in the end it did not have quite the ultimate grip of the Michelin or Bridgestone tires. The BFGoodrich g-Force T/A KDW 2 proved fast, too, but lacked the balance of the Michelins or crisp steering of the Yokohamas.
In the wet, our team found a more noticeable difference across the test group. Out in front again was the Pilot Exalto PE2. This tire provided ample wet grip, especially around the skidpad portion of the track where it felt locked in and stable. Nearly 0.6 second behind in 2nd place was the Potenza RE760 Sport which displayed moderate understeer. Care needed to be taken to avoid inducing the understeer, as once started it took some time for the front tires to regain full grip. Just 0.01 second behind was the g-Force T/A KDW 2. Instead of the Bridgestone's understeer, the KDW 2 displayed plenty of front-end traction coupled with some oversteer tendency when exiting each corner. The S.drive offered appropriate levels of wet grip but lacked the ultimate traction to match the others in the test feeling somewhat slippery, especially during acceleration and hard braking.
BFGoodrich g-Force KDW 2 (Ultra High Performance Summer): The BFGoodrich g-Force T/A KDW-2 (KDW for Key feature: Dry and Wet traction, the "2" is our addition and identifies that this is the second generation g-Force T/A KDW) is the Ultra High Performance Summer tire that was developed to provide a blend of a dramatic-looking, ultra high performance tread design with superior dry and wet road performance.
Bridgestone Potenza RE760 Sport (Ultra High Performance Summer): The Potenza RE760 Sport is Bridgestone's Ultra High Performance Summer tire developed for drivers of sports cars, sporty coupes and performance sedans who want to maximize sport driving pleasure without abandoning treadwear. The Potenza RE760 Sport is designed to deliver sharp response along with traction in wet and dry conditions. Read more.
Michelin Pilot Exalto PE2 (Ultra High Performance Summer): The Pilot Exalto PE2 is Michelin's entry level Ultra High Performance Summer tire designed to raise both the status and performance of small sporty cars that use low profile-sized tires. The Pilot Exalto PE2 was inspired by Michelin's World Rally Championship (WRC) tire design and architecture and was developed to provide crisp and responsive handling in both wet and dry conditions. Read more.
Yokohama S.drive (Ultra High Performance Summer): The S.drive ("Sport drive") radial is Yokohama's Ultra High Performance Summer tire developed for the drivers of sports cars, sporty coupes and performance sedans. The S.drive radial is designed to use Yokohama's technological advancements to deliver extraordinary grip and handling on both wet and dry roads. Read more.
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