June 19, 2015
Nearly everything evolves over time - true for living things, true for cars, and definitely true for tires. The basic process to design and build passenger car tires may not have changed all that much, but many of the components that go into making them have, and more importantly what tires are capable of doing has evolved to the point that the father of the pneumatic tire, John Boyd Dunlop, might not recognize some of them beyond still being round and black.
Nowhere is this more apparent than at the top of the street tire food chain, in the Extreme Performance Summer tire category. Over the past decade, this category has evolved from a few niche products to a full array of tires from many brands delivering dry performance and handling for the street and track that was unimaginable just a few years ago. Once focused solely on ultimate dry performance at the expense of everything else, other attributes are now evolving too, as sometimes road manners, treadwear and even wet traction are improving along with continuing gains in ultimate dry performance. In addition to watching the category’s family tree flourish with an ever-growing list of new flagship products developed to entice enthusiasts and track/autocross drivers, we’re also seeing product life cycles get shorter. Last year’s hot performer might turn into this year’s old news that then becomes updated or even replaced a year or two from now. Survival of the fittest, or fastest, as it were.
This time around we’re treated to three new products in the Extreme Performance Summer category. BFGoodrich is following a path they’ve taken previously for their DOT Track and Competition tires that starts with an existing design and modifies it with a new compound, trading off some treadwear to gain ultimate grip and lower lap times. So, too, for the new g-Force Rival S, which comes out of the same mold as the original g-Force Rival, but rides on a new tread compound designed to come up to optimum temperature more quickly during dry autocross and sprint track use, while also improving wet traction.
Bridgestone’s new tire, the Potenza RE-71R, resurrects an old product name from their performance tire heyday in the 90s. Updated with over 20 years of learning and technological advances, the Potenza RE-71R features a newly developed tread compound and a highly tuned internal construction that maximize contact with the pavement to boost performance.
Kumho was a player in the early days of the Extreme Performance Summer tire category, but has been absent for a while. They’ve returned with the Ecsta V720, which builds on a tread pattern already available in Asia. Tires for the North American market get a unique tread compound and internal structure tuned specifically for the way performance drivers in this part of the world use their tires.
To see how these three new players perform, the Tire Rack team conducted a Real World Road Ride and Performance Track Drive comparing them with one of last year’s newest and top performers, the Hankook Ventus R-S3 (Version 2). Our evaluation used 2014 BMW F30 328i sedans fitted with new, full tread depth 245/40R18 tires mounted on 18x8.0 wheels.
Our 1/3-mile per lap test track course includes 90-degree street corners, a five-cone slalom 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.
Extreme levels of dry weather performance and handling are the reasons these tires exist, and on our test track none disappointed. The Bridgestone Potenza RE-71R stood out, with quick outright speed and impressive traction in all directions - cornering, braking and especially accelerating. It also delivered amazing precision and exceptional communication to the driver. This characteristic helped all of our drivers maximize the tire’s performance from the first corner, and nearly everyone clicked off very consistent lap times.
The Kumho Ecsta V720 followed close behind, providing predictable handling, good communication of its limits and very high traction level. Track performance of the BFGoodrich g-Force Rival S was a small step back from the leaders, and while still reasonably quick, didn’t have the steering response, precision or clear communication to the driver of the faster tires. Right behind the Rival S was the Hankook Ventus R-S3 (Version 2). One of the top new tires the previous year, it’s now pushed to fourth fastest among a relatively tight group this time around as the newer tires from Bridgestone, Kumho and BFGoodrich move the performance needle forward. In the end, there is a pecking order to track performance, but all four of these tires are very capable in the dry, and will provide better ultimate handling and quicker lap times than even the best Max Performance Summer tire.
As we watch the dry performance level of Extreme Performance Summer tires evolve and march ever-higher, we’re also seeing what is essentially a nuclear arms race play out as tire brands really push the performance limits of true street tires. For the first time during our track testing we’re seeing tread rubber marbles ("clag") form just off the driving line in high-load corners. During track duty these tires are sacrificing themselves as they lay down fast lap times. It’s of little surprise given the fast pace of the top tires, but brings with it noticeably higher wear rate on the BFGoodrich, Bridgestone and Kumho than we’ve encountered in past tests of Extreme Performance Summer tires. Now one of the old guard, the Hankook’s treadwear rate was visibly less than on the other three tires, and similar to what we’ve seen in past testing of other Extreme Performance tires.
Impressive dry performance isn’t the only story with these tires. In the early days of the Extreme Performance Summer tire category, high wet traction was abandoned in the search for maximum dry grip, and up until recently this was still the case. We saw the initial signs of this trend changing when we first tested the Hankook Ventus R-S3 (Version 2) in 2014, which performed remarkably well in warm, wet conditions. This time around we find all four tires in the test delivering wet traction that is beginning to approach that of good Max Performance Summer tires, the traditional go-to category to find the highest levels of wet grip.
In our wet track test, the spread in lap times across all four tires was slightly less than a quarter of a second, one of the narrowest margins we’ve encountered across a test group. The Potenza RE-71R repeated its friendly nature found in the dry, proving easy for our drivers to maximize lap after lap. The g-Force Rival S, Ecsta V720 and Ventus R-S3 (Version 2) were close behind. Measured tests of cornering traction and ABS-assisted panic stop distances mirrored lap times with surprisingly similar results for all four tires.
It’s important to note our wet test focuses on traction, and doesn’t include speed and water depth to create appreciable hydroplaning. Anecdotally the limited void space and shallower molded starting tread depth of these Extreme Performance Summer tires causes hydroplaning at lower speeds and with more abrupt onset than with other summer performance tires that feature less aggressive tread patterns.
Our 6.0-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.
As the category name implies, these are extreme tires designed to perform. And like most things that are this specialized there are trade-offs. The steps needed to deliver this level of handling and traction results in a sacrifice in ride and noise comfort during everyday driving. As a consequence, we found the top performing tires on the track to be rather punishing during everyday driving on the road. One can make the argument that given the focus of these tires, road manners are of little importance. But buyers should beware of what they’re getting. If you drive a fairly quiet performance car, the impact on everyday comfort is sizeable. If you install these Extreme Performance Summer tires on a more modified, stiffly sprung and loud car, then it’s less apparent.
All four of these tires handle very well at the light-duty levels found driving along with surrounding traffic. Steering feels direct, response is very linear, and the communication to the driver of what is going on is clear and precise.
From a noise and comfort standpoint, several of these tires stand out, and not in a positive way. The noise level of the Kumho Ecsta V720 can only be described as loud, all the time. Once speeds climb past 20mph a steady drone from its tread pattern is heard. The unsuspecting driver might think a wheel bearing is failing, as the growl can be fierce and rises and falls in direct sync with speed. Nearly as loud is the Bridgestone Potenza RE-71R. This tire also makes a constant, steady whir easily heard above the surrounding ambient noise from wind and adjacent traffic. In addition, the Potenza RE-71R emits a unique sound when it crosses tar strips, paint stripes or rolls over certain smooth pavement surfaces, almost like the sound of sticky tape being pulled off plastic. These two tires are possibly the loudest passenger car street tires we have ever tested out on the road.
Relative to the noise from the Kumho and Bridgestone tires, the BFGoodrich and Hankook tires brought welcome relief to the aural onslaught. But make no mistake, even these tires are considered loud when compared with less extreme summer performance tires. The blocky-looking tread pattern of the g-Force Rival S gets the closest of this test group to producing noise levels that approach reasonable. The Ventus R-S3 (Version 2) generates a noticeable growl, but it’s much more distant than the worst offenders of the group.
Given the sporty nature of these tires, ride quality is not a high priority. Consequently, all four tires deliver rather firm rides, with the Rival S and Ventus R-S3 (Version 2) tires riding the best, and the Potenza RE-71R and Ecsta V720 tires feeling quite firm, to even somewhat harsh when encountering large, sharp impacts.
Our Real World Road Ride features a relatively flat 6.0-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 each tire 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.
| Tire | Test MPG* | Gallons/Year @ 15,000 Miles |
% vs. Most Efficient |
|---|---|---|---|
| BFGoodrich g-Force Rival S | 30.0 | 500.0 | -- |
| Bridgestone Potenza RE-71R | 29.9 | 501.7 | -0.33% |
| Hankook Ventus R-S3 (Version 2) | 29.9 | 501.7 | -0.33% |
| Kumho Ecsta V720 | 29.7 | 505.1 | -1.01% |
| *Our evaluation used Race Technology DL1 data loggers to record true distance travelled. | |||
Given their extreme traction focus, none of the tires in this test were designed with low rolling resistance as a high priority. Consequently our testing didn’t show a significant difference across the group, with just 3/10ths of a mile per gallon difference between the lowest and highest observed fuel consumption. For drivers travelling 15,000 miles per year the difference from lowest to highest works out to just 5.1 gallons of premium gasoline, which at the current cost of $3.00/gallon amounts to just over $15 per 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.
If you want the highest level of traction and handling in a true street tire and are willing to give up civilized manners to get it, then an Extreme Performance Summer tire fits the bill. All four of the tires in our test deliver amazing traction and handling in dry conditions along with impressive wet grip. The newest designs offer the best outright performance, but are evolving to be much less street-friendly in the process.
Subjectively the BFGoodrich g-Force Rival S outscores the other tires by a small margin, combining strong performance with reasonable road manners. But when it comes to ultimate dry and wet performance among this group, the Bridgestone Potenza RE-71R is the top rung on the evolutionary ladder. The Kumho Ecsta V720 gives the Potenza RE-71R a run for its money by delivering impressive dry performance, but brings along road manners so extreme that it’s not for the faint of heart and not well suited to daily commuter duty. The Hankook Ventus R-S3 (Version 2) holds its own against tough competition, but from an outright performance perspective it’s clear that newer designs are a little faster.
BFGoodrich g-Force Rival S (Extreme Performance Summer): The g-Force Rival S is BFGoodrich’s Extreme Performance Summer tire developed for sports car, muscle machine and pro-touring car driving enthusiasts who want their tires tuned to lower their run times in solo, autocross, track attack and hill climb events. Created with razor-sharp reflexes, the g-Force Rival S is designed to raise the limits by delivering extreme grip that’s extremely predictable. However, like all Extreme Performance Summer tires, it is not intended to be serviced, stored or driven in near- and below-freezing temperatures, through snow or on ice. Read more.
Bridgestone Potenza RE-71R (Extreme Performance Summer): The Potenza RE-71R is an Extreme Performance Summer tire developed for serious sports car, sports coupe and performance sedan driving enthusiasts looking for Bridgestone’s fastest DOT-legal street radial. Starting with a clean-sheet approach and a virtual slick tread, all of the design features were fine-tuned to maximize performance, traction, handling and control. Performance-tuned for dry and damp conditions, the Potenza RE-71R, like all Extreme Performance Summer tires, tires are not intended to be serviced, stored or driven in near- and below-freezing temperatures, through snow or on ice. Read more.
Hankook Ventus R-S3 (Version 2) (Extreme Performance Summer): Ventus R-S3 Version 2 (Z222) Extreme Performance Summer tires were developed for serious sports car, sports coupe and performance sedan enthusiasts looking for race-minded street tires that can also meet the demands of autocross, drifting and track events. Designed to further reduce the performance gap between street and track tires, the Ventus R-S3 Version 2, like all Extreme Performance Summer tires, is not intended to be serviced, stored or driven in near- and below-freezing temperatures, through snow or on ice. Read more.
Kumho Ecsta V720 (Extreme Performance Summer): The Ecsta V720 is Kumho’s Extreme Performance Summer tire developed for passionate driving enthusiasts looking for a tire that was bred for the track and domesticated for civil society. Designed to deliver Kumho’s ultimate performance on dry pavement and cool confidence on wet, the Ecsta V720 delivers unusually long life for a tire that lives this fast. Like all summer tires, it’s not intended to be driven in near- or below-freezing temperatures, through snow or on ice. Read more.
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