June 25, 2010
Street/Sport Truck All-Season tires offer a sporty blend of handling, reasonable ride comfort and some all-season capability. Many of today's performance-oriented SUVs and CUVs are designed around the characteristics and capabilities of these tires. But just as vehicles vary, so, too, do the characteristics of different tires grouped in the same category.
To find out more about the different personalities of several tires in the Street/Sport Truck All-Season category we decided to put a trio through the paces by conducting a Real World Road Ride and Performance Track Drive. We compared the new Firestone Destination ST, Kumho Ecsta STX KL12 and Pirelli Scorpion Zero. Our evaluation used 2009 Porsche Cayenne V6s fitted with new, full tread depth 255/55R18 tires mounted on 18x8.0" wheels.
Our 6.6-mile loop of expressway, state highway and county roads provides a great variety of road conditions that include 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.
Street/Sport Truck All-Season tires are targeted at the sporty side of the SUV/pickup market, and our trio fit the bill nicely. The Kumho Ecsta STX KL12 felt the most nimble of the group with quick steering response. The Pirelli Scorpion Zero followed, with a smooth and linear feel to the steering wheel. The Firestone Destination ST rounded out the group, showing competitive handling traits that were a little less responsive than the others.
The Scorpion Zero and Destination ST were close together, leading for overall ride comfort. Both did a good job controlling the harshness of most of the impacts encountered along our test route. The Ecsta STX KL12 paid a penalty for its responsive steering with a firm, almost harsh, ride when compared to the Pirelli and Firestone tires.
Pirelli also led the group in noise comfort, producing minimal noise as it rolled along. The Firestone tire produced a modest growl from its aggressive-looking tread pattern, while the Kumho was in a league of its own as its aggressive directional tread pattern produced a fair amount of tread noise at all speeds and across all road surfaces.
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.
The typical SUV or CUV doesn't spend its day driving at the limit of traction. But if you are tempted to have some fun along your favorite twisty back road or expressway on-ramp, or more importantly, when facing an emergency avoidance maneuver it's good to know how your tires will behave.
In dry conditions, the Kumho Ecsta STX KL12 and Pirelli Scorpion Zero were nearly tied for fastest lap time, with the slightest advantage going to the Kumho. Subjectively, the Pirelli felt somewhat more refined, displaying poise and good overall grip. The Kumho was very nimble, which helped it respond to driver inputs, but it didn't seem to have the ultimate grip to match. The Firestone Destination ST was a close third for lap time but it didn't have quite the response of the other two.
In the wet, the differences were more apparent. Here the Pirelli felt better than the other two, again feeling poised and easy to control. The Kumho was able to lap the track almost as quickly as the Pirelli, due in part to its responsive steering. But it lacked the ultimate wet grip of the Scorpion Zero that was most evident under hard braking. The Firestone delivered competitive handling, but lacked the overall traction of the Scorpion Zero or the responsiveness of the Ecsta STX.
Our Real World Road Ride features a relatively flat 6.6-mile loop of 65 mph expressway, 55 mph state highway and 40 mph county roads along with two stop signs and one traffic light every lap. Our team drove approximately 500 miles over the course of several days. Since we wanted to compare fuel consumption results that typical drivers would experience, our drivers were instructed to maintain the flow of traffic by running at the posted speed limits and sustain the vehicle's speed using cruise control whenever possible. They did not use hypermiling techniques to influence vehicle fuel economy.
@ 15,000 Miles
|% vs. Most Efficient|
|Firestone Destination ST||17.8||842.7||-2.81%|
|Kumho Ecsta STX KL12||17.8||842.7||-2.81%|
|Pirelli Scorpion Zero N0||18.3||819.7||--|
|*Our evaluation used Linear Logic ScanGauge II automotive computers to record fuel consumption, and Race Technology DL1 data loggers to record true distance travelled.|
Many of today's Original Equipment (O.E.) tires are designed with at least some emphasis on reducing rolling resistance, while many non-O.E. tires focus their design priorities in other areas. To that point, the Pirelli Scorpion Zero used in our test is a Porsche O.E. fitment. It showed a modest MPG advantage over the other two tires which are not Original Equipment on any vehicle. Based on our results the 0.5 mile per gallon difference between our lowest and highest observed fuel economy would result in an annual difference of about 23 gallons of premium gasoline. At the current cost of $2.75/gallon, it would amount to about $63 for drivers traveling 15,000 miles a year.
It's important to note our test's fuel consumption measurements follow consistent procedures designed to minimize variables that could influence the results, however they do not represent an exhaustive long-range fuel consumption study. While our procedures require the test vehicles in each convoy to run under the same prevailing conditions, the week-to-week differences in ambient temperatures, barometric pressures and wind speeds that we experience over a season of testing can influence vehicle fuel consumption and prevent the absolute mpg values of this test from being compared directly against those of others.
Larger differences in consumption between tires may indicate a difference that might be experienced on the road, while smaller differences should be considered equivalent. As they say, your mileage may vary.
Firestone Destination ST (Street/Sport Truck All-Season): The Destination ST is Firestone's Street/Sport Truck All-Season tire developed for the drivers of performance pickups, crossovers and sport utility vehicles looking to combine year-round capabilities with a bold appearance. The Destination ST is designed to provide all-season traction and handling, even in light snow.
Kumho Ecsta STX KL12 (Street/Sport Truck All-Season): The Ecsta STX KL12 is Kumho's Street/Sport Truck All-Season radial developed to meet the needs of sport utility vehicle, crossover vehicle and performance pickup drivers. The Kumho Ecsta STX KL12 blends an eye appealing appearance with year-round, on-road performance and traction, even in occasional light snow. Read more.
Pirelli Scorpion Zero (Street/Sport Truck All-Season): Derived from Pirelli's legendary P Zero performance tires, the Scorpion Zero is a Street/Sport Truck All-Season tire for sport utility vehicles and pickup trucks. The Scorpion Zero was designed to provide year-round traction and handling for drivers who operate their light truck vehicles primarily on-road in various weather conditions, including very occasional light snow. Read more.
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