June 11, 2010
2011 BMW E92 328i Coupe
Ultra High Performance Summer tires are designed to deliver very good dry and wet traction, along with sporty handling and reasonable road manners. They're the perfect choice when it's time for new tires on your sporty coupe or performance sedan, or if you just want to add a little zip to your daily driver.
To find out how a group of popular Ultra High Performance tires compares to one another, the Tire Rack team conducted a Real World Road Ride and Performance Track Drive to evaluate the BFGoodrich g-Force Sport, new Firestone Firehawk Wide Oval Indy 500, Kumho Ecsta SPT KU31 and the Yokohama S.drive. Our evaluation used 2010 BMW E92 328i coupes fitted with new, full tread depth 225/45R17 tires mounted on 17x8.0" 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.
We've tested the Yokohama S.drive before, and out on the road it displayed its characteristic responsive steering and stable handling. The Firestone Firehawk Wide Oval Indy 500 also drove well, with steering that felt direct and linear. The BFGoodrich g-Force Sport handled nicely, too, with a distinctive weighted feel in the steering wheel that required just a little more effort to turn the wheel. Rounding out the group was the Kumho Ecsta SPT KU31, which felt a little less precise and responded a little more slowly than the others.
Thankfully the nimble handling of this group doesn't mean giving up all semblance of ride comfort. The S.drive does an admirable job at softening the fine high-frequency ripples and the larger impacts along our route. The Firehawk Wide Oval Indy 500 also did a good job absorbing most of the medium and larger impacts. The g-Force Sport felt a little harsher than the Yokohama and Firestone tires, while the Ecsta SPT seemed less-refined than the others, sending more of the road's imperfections in to the driver.
As a group, all four tires in this test were found to provide competitive noise levels as they went down the road. The S.drive stood out, doing the best job by producing the least tread pattern noise over the variety of surfaces we encountered. The Firehawk Wide Oval Indy 500 was also found to be reasonably quiet, but some of our team noticed a subtle but distinct high-pitch whine at higher speeds. The g-Force sport generated a low growl, and the Ecsta SPT had a louder but broad tone to its tread noise.
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.
In dry conditions lap times from first to fourth were separated by one of the smallest margins we've encountered, with less than 0.15 seconds covering the group. But how each got there was not as similar, with the personality of each tire showing itself by a wider margin.
The Yokohama S.drive was the subjective favorite thanks to its crisp steering and stable handling. The Firestone Firehawk Wide Oval Indy 500 used its responsive handling and excellent braking capability to post the quickest lap time, but didn't have the precise feel of the Yokohama. BFGoodrich's g-Force Sport also handled well, with good overall grip. The Kumho Ecsta SPT posted a quick lap time, but did not show the poise or balance of the others.
In the wet roles were reversed somewhat. This time, the Ecsta SPT was the clear standout, with the grip to provide our drivers with the control needed to drive quickly. The S.drive followed, again showing its responsive steering and good overall traction. The g.force Sport performed well, but didn't have quite the overall poise or traction of the Kumho and Yokohama tires. Trailing the group was the Firehawk Wide Oval Indy 500, which did not display the ultimate traction of the other three tires.
Fuel Consumption Results
Our Real World Road Ride uses a 6.6-mile loop of public roads with little elevation change. It includes 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.
The observed vehicle fuel economy recorded while driving on each tire is shown here:
@ 15,000 Miles
|% vs. Most Efficient|
|BFGoodrich g-Force Sport||26.4||568.8||-5.55%|
|Firestone Firehawk Wide Oval Indy 500||27.0||556.1||-3.20%|
|Kumho Ecsta SPT KU31||27.3||549.5||-1.98%|
|*Our evaluation used Linear Logic ScanGauge II automotive computers to record fuel consumption, and Race Technology DL1 data loggers to record true distance travelled.|
While none of the tires in this test were designed with low rolling resistance as a high-priority, we did find a difference in observed vehicle fuel economy. Based on our results the 1.5 mile per gallon difference between our lowest and highest observed fuel economy would result in an annual difference of about 30 gallons of premium gasoline. At the current cost of $2.75/gallon, it would amount to about $82 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.
BFGoodrich g-Force Sport (Ultra High Performance Summer): The g-Force Sport is BFGoodrich's Ultra High Performance Summer tire developed for the drivers of sport compact sedans and coupes looking to combine good looks, dry handling and affordable prices. The g-Force Sport is designed to provide traction in dry and wet conditions, however it is not intended to be driven in near freezing temperatures, through snow or on ice. Read more.
Firestone Firehawk Wide Oval Indy 500 (Ultra High Performance Summer): The Firehawk Wide Oval Indy 500® tire's name represents three eras of Firestone heritage while the tires themselves provide today's sports car, sporty coupe and performance sedan drivers with Ultra High Performance Summer tire proficiency. The Firehawk name is from the present where it is shared with the racing tires Firestone manufacturers to support today's IndyCar® championship. The Wide Oval name comes from Firestone's first low profile tires that helped revolutionize high-performance street tires in the late 1960s. And INDY 500® celebrates one of the longest relationships in motor sports where winning the first Indy 500® in 1911 and all of Firestone's other victories at the Greatest Spectacle in Racing have established a rich tradition backed by a history of performance.
Like all summer tires, Firehawk Wide Oval Indy 500 tires are not intended to be driven in near-freezing temperatures, through snow or on ice. Read more.
Kumho Ecsta SPT KU31 (Ultra High Performance Summer): The Ecsta SPT (KU31) is Kumho's Ultra High Performance Summer tire developed for sports cars, coupes and sedans. The Ecsta SPT was designed to offer grip, handling, comfort, wear and good looks in order to provide enthusiastic drivers the ability to "Drive Hard 'Go Big' Look Good." Ecsta SPT tires are not intended to be driven in near-freezing temperatures, through snow or on ice. 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. Like all summer tires, the S.drive radial is not intended to be driven in near-freezing temperatures, through snow or on ice. Read more.
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