July 9, 2010
As the world continues to focus on being more ecologically friendly, tire manufacturers have begun to expand their role to help lower the tire's impact on the environment. In addition to developing technologies that help reduce the tire's contribution to fuel consumption through lower rolling resistance, new manufacturing methods use more eco-friendly raw materials such as non-aromatic oils in place of petroleum, while other tires are designed to simply last longer as a way to reduce the total number of tires used.
Early on, eco-focused tires were only available in select sizes for drivers of hybrid and ultra-efficient vehicles. Today, a growing number of eco-focused tire lines are becoming available in a wider variety of sizes in an effort to gain widespread use by the everyday consumer.
Measuring fuel economy improvements in the lab is one thing, but we wanted to find out how several of the newest mainstream eco-focused all-season tires perform in everyday conditions. So, the Tire Rack team conducted a Real World Road Ride and Performance Track Drive to find out. We compared four tires marketed as eco-friendly and fuel-efficient from the Passenger All-Season and Standard Touring All-Season categories.
While all of these tires are designed to focus on reducing vehicle fuel consumption over their life, the technologies they employ to combine low rolling resistance qualities with on-road capabilities vary from manufacturer to manufacturer. The Continental ProContact with EcoPlus Technology features temperature activated polymers and +Silane additives to improve treadwear and fuel efficiency while enhancing grip on slippery roads. The Goodyear Assurance Fuel Max features a fuel-saving tread compound molded into a dual-zone tread design to provide confident dry and wet traction. The Kumho eco Solus HM KR22 is the first in their family of passenger and light truck tires formulated to be less impactful on the environment. The Michelin HydroEdge with Green X helps deliver fuel efficiency by requiring less effort from the engine along with a unique contact patch shape that evenly distributes driving forces. While all of the tires in this test are designed to deliver relatively long mileage (ProContact EcoPlus 80,000, Assurance Fuel Max 65,000 and HydroEdge with Green X 90,000), the eco Solus HM KR22 has been designed to deliver up to 100,000 miles of wear.
Our evaluation used 2011 BMW E92 328i coupes fitted with new, full tread depth 205/55R16 tires mounted on 16x7.5" 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.
Out on the road, the Continental ProContact with EcoPlus Technology displayed a modest advantage in ride comfort over the Michelin HydroEdge with Green X. Both tires did a good job controlling the bumps and jostling when driving over expansion joints and patched pavement. The Goodyear Assurance Fuel Max ranked third, allowing a bit more of the road's imperfections to find their way to the driver. Close behind was the Kumho eco Solus HM KR22, which felt a little less supple than the others when it encountered bumps in the road.
The ProContact EcoPlus also showed an advantage in noise level, with a relatively quiet tread pattern and muffled impact noises. The Assurance Fuel Max followed, also displaying modest tread noise and just a little additional booming on larger impacts. The eco Solus HM KR22 produced a little more boom on impacts than the Continental and Goodyear tires, while the HydroEdge with Green X generated a modest growl from the tread pattern and a noticeable ping on sharp impacts.
When it came to light road handling, the HydroEdge with Green X was a clear favorite with our team, thanks to this tire's stable and responsive handling. The ProContact EcoPlus handled well, too, with predictable but somewhat less responsive steering. The Assurance Fuel Max didn't feel quite as nimble as the Michelin and Continental tires, while the eco Solus HM KR22 rounded out the group with a steering that felt somewhat sluggish in comparison to the others.
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.
On the track in the dry, we again found the Michelin HydroEdge with Green X to be responsive, stable and confidence inspiring, especially under hard braking. Right on its heels was the Continental ProContact EcoPlus that also felt capable and sure-footed when driven at the limit. The overall grip level of the Goodyear Assurance Fuel Max did a good job holding on to the track surface, but didn't feel quite as composed as the HydroEdge with Green X or ProContact EcoPlus tires. The Kumho eco Solus HM KR22 was somewhat disconnected and out of its element when asked to respond to driver inputs, accelerate or brake while driving at the limit.
With this group of tires we experienced one of the widest ranges in traction that we have ever found during our wet track test. This time the ProContact EcoPlus showed clear leadership, with plenty of competence and poise. The HydroEdge with Green X followed closely thanks to its characteristic crisp steering response, but it just didn't have quite the wet traction of the ProContact EcoPlus. The Assurance Fuel Max displayed good predictability, but with less overall grip than the ProContact EcoPlus and HydroEdge with Green X. Rounding out the group was the very slippery eco Solus HM KR22, which struggled for wet traction making it challenging to control during aggressive maneuvers.
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.
The observed vehicle fuel economy recorded while driving on each tire is shown here:
@ 15,000 Miles
|% vs. Most Efficient|
|Continental ProContact w/EcoPlus Technology||28.1||533.8||-0.36%|
|Goodyear Assurance featuring Fuel Max Technology||28.2||531.9||---|
|Kumho eco Solus HM KR22||27.8||539.6||-1.44%|
|Michelin HydroEdge with Green X||27.8||539.6||-1.44%|
|*Our evaluation used Linear Logic ScanGauge II automotive computers to record fuel consumption and Race Technology DL1 data loggers to record true distance travelled.|
The tires in this test were designed with low rolling resistance as a high priority, but among the four test tires we did not find a significant difference in observed vehicle fuel economy. The 0.4 miles per gallon difference between our lowest and highest recorded fuel economy measurements would result in an annual difference of only about 8 gallons of premium gasoline at a current cost of about $21 (at $2.75/gallon) 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.
Continental ProContact with EcoPlus Technology (Standard Touring All-Season): The ProContact with EcoPlus Technology is Continental's Standard Touring All-Season tire developed for coupes, sedans, minivans and crossover vehicles. The ProContact EcoPlus is designed to enhance driving pleasure, save fuel and maintain wet braking grip while providing long wear and all-season traction, even in light snow. Read more.
Goodyear Assurance featuring Fuel Max Technology (Passenger All-Season): The Assurance featuring Fuel Max Technology is Goodyear's mid-tier Passenger All-Season tire designed for the drivers of cars, coupes, vans and crossover vehicles looking for affordably priced tires offering long wear, wet traction and low rolling resistance as some of their top priorities. The Assurance Fuel Max is designed to provide year-round confidence in wet, dry and wintry weather conditions, including in light snow, as well as offers lower rolling resistance to enhance vehicle fuel economy over the tire's lifetime. Read more.
Kumho eco Solus HM KR22 (Standard Touring All-Season): The eco Solus HM (High Mileage) KR22 is Kumho Tire's Standard Touring All-Season tire developed for the drivers of family coupes, sedans and minivans. The eco Solus HM is designed to offer a combination of extra long wear, low noise and good ride with competent handling and enhanced all-season traction, even in light snow.
Michelin HydroEdge with Green X (Passenger All-Season): The Michelin HydroEdge with Green X radial is a premium Passenger All-Season energy-efficient tire developed to meet the needs of the drivers of family coupes, sedans and minivans looking for great tread life, fuel efficiency and all-weather traction. The HydroEdge with Green X was designed to combine long treadwear and low rolling resistance with superb hydroplaning resistance and year-round traction, even in light snow.
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