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TREADING LIGHTLY

Sydney Morning Herald

Saturday February 6, 2010

RICHARD BLACKBURN

Are low rolling resistance tyres kinder to the planet and your wallet? RICHARD BLACKBURN investigates. THE "save money and save the planet" sales pitch is well worn in the car industry these days.In a brave new world where fuel use and carbon dioxide exhaust measurements are scrutinised as never before, car companies are going to great lengths to demonstrate their green credentials.If they're not literally planting trees at their manufacturing sites, they're telling you how many theoretical trees they have planted by making their cars more efficient.Click on to some websites and it'll be easier to calculate the CO2 emissions of one car versus a rival than to find a price. Toyota's Prius website will even tell you that running a Ford Falcon instead of a Toyota Prius for a year is the equivalent of spraying 814 aerosol cans until they are empty.It's no wonder, then, that some tyre makers have jumped on the green bandwagon. Visit any tyre dealer these days and you'll see promotional pamphlets spruiking environmentally friendly rubber that will reduce your carbon footprint and save you money at the pump.Both Hankook and Michelin have entire websites dedicated toexplaining the benefits of, and the technology behind, their low rolling resistance tyres.The Michelin site even has areal-time calculator that estimates the fuel saved globally by the company's low rolling resistance tyres. The figure has just ticked over the 12-billion-litre mark. Michelin has been marketing low rolling resistance tyres since 1992.To the untrained eye, changing a tread pattern or tyre compound would seem like fiddling at the edges of fuel consumption figures. But you may be surprised by just how much difference a strip of rubber can make to the amount of fuel you use and the amount of CO2 your car emits.Friction from tyres accounts for about one-fifth of a car's fuel consumption in other words, every fifth time you fill up, you're filling up for the tyres.The latest range of "green" tyres makes some impressive claims about fuel consumption gains and CO2 emission reduction, so we thought we'd put them to the test in the real world, using three identical Toyota Aurions.We covered more than 2000 kilometres in each vehicle, driving in convoy (but at a sufficient distance to avoid any aerodynamic advantage) to ensure that weather conditions, traffic and speeds were as close to identical as is practical in areal-world test. As a control tyre, we used the Dunlop SP Sport provided as original equipment on the Aurion out of the Toyota factory in Altona, Victoria.The cars were all Toyota Aurion Presaras, the range-topping model that rides on 17-inch wheels. But the "green" tyres we sourced from Michelin and Hankook are only available in 16-inch sizes, so all three were fitted with 16-inch wheels, with Toyota's blessing (the Dunlop 16-inch wheels and tyres we used were from an entry-level Aurion AT-X).The exercise included a mix of city driving, dynamic testing on a racetrack and freeway cruising.The two "green" tyres we chose were the Michelin Primacy LC Green-X and the Hankook Enfren.Both deliver fuel savings through the use of a special rubber compound that reduces the rolling resistance, or friction, of the tyre as it rolls along the road surface.The magic ingredient in the compound is silica, one of the most abundant minerals in the Earth's crust.It is used in a range of industries and appears in some form or another in glass bottles, optic fibres, toothpaste and porcelain, among other things.Silica reduces the friction between rubber molecules in the tyre, which means less energy is lost through the tread, in turn delivering better fuel consumption.Hankook claims the Enfren has 20 per cent less rolling resistance than a conventional tyre. But how does that translate to lower fuel bills? Hankook says its low rolling resistance tyre reduces fuel consumption by between 2 per cent and 7.5 per cent (depending on which laboratory or real-world test it quotes).That might not sound like much but over the 60,000-kilometre average life of a tyre, it's not insignificant.Based on a Ford Falcon that's driven 15,000 kilometres a year, with a fuel price of $1.30, a 2 per cent improvement would save about $165 over the life of the tyre.But our independent test shows the actual savings could be three times that amount. After our 2000-kilometre loop, the Aurion fitted with Michelin's low rolling resistance tyre had used 186 litres of fuel, compared with 199 litres for the car fitted with the standard Dunlops. That translates to a saving of about 6 per cent.Around town, the savings were slightly better, with the Michelins using 7.7 per cent less than the car on Dunlops over almost 450 kilometres.The Hankooks also delivered fuel savings, although not quite as dramatic as the Michelins. The Hankook-shod Aurion used just less than 191 litres, 4 per cent less than the Dunlop-fitted car.In the city loop, the Hankook tyres were 3.6 per cent more efficient.All three cars achieved better consumption than their official fuel label claim of 9.9 litres per 100 kilometres.The Michelin-shod Aurion averaged 9.04L/100km over the entire 2063-kilometre journey, while the Hankook car used 9.25L/100km and the Dunlop 9.65L/100km. On the freeway legs of the test, the trip computer on the Michelin-shod Aurion dipped as low as 7.1L/100km, which is impressive for a large car with 200kW of power at its disposal. Around town, it used marginally more than the official label at 10.08L/100km.As a final safeguard, we took one car and drove it three times over a 175-kilometre loop of mostly freeway driving, changing tyres and refuelling after each loop.The results were similar to those we achieved when we drove the three cars in convoy, although the Michelin tyres used 8 per cent less fuel and the Hankooks 6 per cent.The other key element of our results was that we checked tyre pressures and set each one to the manufacturer's recommendation. Tyre companies estimate you can save between 3 per cent and 5 per cent on your fuel bills simply by having your tyres inflated to the right pressure.If you buy green tyres and check regularly to make sure they're inflated to the right pressure, our test indicates you could cut your fuel bill by as much as 10 per cent. And the best news is that the potential savings from more fuel-efficient tyres are available to both new and used-car buyers.But the dollar savings are only part of the equation. Less fuel means less CO2. Over our 2063-kilometre test, the Aurion running on the standard Dunlop tyres emitted about 458 kilograms of CO2, while the car running on the Michelins emitted about 429 kilograms.Over a year, the savings on a large family car could equate to 300 kilograms less CO2. If you were driving a thirsty off-roader or high-performance V8 around town, that figure could double.Over the average 10-year life of a car, that could mean three tonnes to six tonnes less CO2, equivalent to the absorption of between 570 trees and 1140 trees.Michelin spokesman Adam Storey says about 70 per cent of Michelin's tyre range carries its Green-X moniker, denoting the low rolling resistance compound.Tyre sizes range from 13-inch for small cars up to 17-inch for large family cars such as the Falcon and Commodore. From late this year it will roll out larger, more performance-focused tyres for sports cars.Michelin also makes Green-X tyres for some commercial vans such as the Toyota HiAce and Volkswagen Transporter and a limited range of options for one-tonne utes. It covers most crossovers, four-wheel-drives and soft-roaders, although there are no heavy-duty off-road Green-X tyres.Storey says Michelin has paid particular attention to making sure the Green-X tyres are as durable and long-lasting as conventional rubber."There's no point in having lower rolling resistance tyres that wear out quicker than regular tyres and end up costing you more," he says.Both Bridgestone and Michelin claim that low rolling resistance tyres last longer than conventional rubber. A Michelin UK study involving fleet drivers found the silica-based tyres lasted up to 25 per cent longer than conventional ones and saved between 4 per cent and 8 per cent in fuel bills.Storey also claims Michelin's green tyres don't make any compromise on handling, ride and noise."Those things depend more on the tread pattern and the stiffness of the tyre's sidewall," he says. "On wet cornering and wet braking, when you really want the tyre to work for you, the silica tyres can actually outperform regular tyres because they get up to operating temperature faster and maintain a more uniform temperature, which is better for grip."We put those claims to the test on the Broadford racetrack in country Victoria, completing several laps in each of our three test mules.We subjected the cars to a slalom run, an emergency-brake move from 100km/h and a "swerve and recover" test, which simulates swerving suddenly to avoid an obstacle.We also tested the grip of each tyre by pushing the cars to their limits on fast laps of the Broadford circuit. Each car was numbered and drivers were asked not to look at the tyres as they got into the cars, ensuring no preconceptions about each brand.The Michelin tyre was the pick of our three testers, with slightly more grip through fast, sweeping corners and less squirming and squealing through the slalom and swerve-and-recover exercises.But the grip levels were not far above the Dunlops, which squealed noticeably but were otherwise OK during the extreme testing.The Hankooks lacked a little grip in the dynamic exercises, particularly in high-speed cornering, where they felt slightly more skate-like on the limit. Some testers noted they squirmed on initial turn-in and the tyre seemed to lean more on its sides when cornering quickly. To be fair, though, with the higher side profile of each tyre, each was leaning heavily on its outer edge as the rubber folded under.Braking distances were similar for all three cars, with each stopping in about 44 metres from 100km/h, according to our satellite-based testing equipment.In day-to-day driving around town, the Hankooks also trailed the two other tyres marginally on ride comfort, although they were quiet on both rough and smooth surfaces. Judges were also looking for minute differences.One tester scored the Dunlop as the pick for all-round honours just. It was the quietest of the three and absorbed bumps slightly better than the others, while providing comparable grip when driven on the limit.Two others picked the Michelins as the best overall compromise, delivering both grip and poise.When you then factor in fuel savings of between 4 per cent and 6 per cent, both low rolling resistance tyres are worth considering. There is a catch, though. Hankook's Enfren range is not cheap. Drive was quoted between $180 and $202 for a 215/60/16 tyre, compared with between $144 and $162 for a standard non-silica tyre of the same dimensions.Hankook says the recommended retail price of the Enfren in that size is $165, while its regular K415 is $135. That equates to a premium of $120-$160, assuming you could get 60,000 kilometres from either set.With fuel savings of about 4 per cent, travelling that same 60,000 kilometres in a car using an average of 10L/100km would save $312. But that's at today's fuel prices; if petrol increases by one-third (a conservative estimate in some experts' eyes), the savings could be more than $415.Michelin says it doesn't charge a premium for its Green-X range, as the majority of its tyres (70 per cent) are low rolling resistance. But its products are generally at the pricier end of the spectrum, with the 215/60/16s we tested $209 each.That's exactly the same recommended price as the Dunlops fitted to the base-model Aurion. Yet the Michelins could save $468 over the life of the tyres, or up to $622 if fuel prices increase by one-third.As fuel prices increase as most people agree they will the potential fuel savings will amplify.Since our test was carried out, Bridgestone released its own eco-friendly brand, the Ecopia. The company says the tyres have been put through "rigorous and extensive independent testing" under Australia's ADR 81/02 standard for measuring fuel consumption.It claims the Ecopia tyres could increase fuel efficiency by 3.3 per cent, which will reduce CO2 output over the life of a set of tyres by 260 kilograms. The saving is based on an average 14,000 kilometres a year for 40,000 kilometres.The tyre is available in sizes to suit most small and medium cars (sizes range from 14-inch to 17-inch), as well as some premium vehicles such as the Lexus IS250 and Mercedes C-Class. It's also much cheaper than the Hankook and Michelin equivalent, at just $148.It isn't available for larger vehicles such as the Holden Commodore and Ford Falcon but Bridgestone says it has a version of its Turanza ER300, the GR90, which incorporates Ecopia technology. That is available for $156 and Bridgestone says it sells at about a 10 per cent premium over the conventional version of the same size.The general manager of marketing for Bridgestone, Stanley Toh, says buyers are generally becoming more eco-conscious."We conducted focus groups globally and within Australia prior to launch and found there was a strong market for the Ecopia product, particularly among consumers who research before they buy and eco-conscious consumers who are drawn to products that make an eco-contribution," he says. "That same research also revealed that while improved fuel economy was important, it was theeco-contribution and safety features of Ecopia that were more compelling."Toh says sales of the Ecopia since its launch in November are well ahead of the company's initial targets.At the moment, green rubber is largely an aftermarket purchase but manufacturers are increasingly fitting silica-based tyres as standard equipment to new cars.Tyre companies are becoming involved in the development of fuel-miser versions of conventional cars. Australia's most frugal car, the Ford Fiesta Econetic, for example, uses low rolling resistance tyres to help achieve its fuel consumption of 3.7L/100km.Michelin has worked with Toyota on the Prius and the Lexus RX400h hybrids, as well as Volkswagen's BlueMotion low-consumption vehicles. Even the humble Holden Commodore adopted low rolling resistance tyres for a model update late last year, although engineers admitted these do compromise slightly on grip.BMW uses low rolling resistance tyres as part of its "efficient dynamics" program, as do Audi's fuel-efficient "e" vehicles and Mercedes-Benz's new E-Class.Car companies are also cuttingtyre-related consumption simply by removing the spare. A spare tyre and the associated tools can weigh about 20 kilograms, adding to fuel consumption. Some are ditching the spare for a tyre-repair kit, or fitting run-flat tyres. Apart from saving weight, the move frees up valuable cargo space. The Fiesta Econetic is one car to offer a repair kit in lieu of a spare.With the growing focus on reducing automotive emissions, there's a good chance the next new car you buy will ride on "green" tyres. But if you're planning to stick with your existing car past its next change of rubber, a low rolling resistance tyre appears to be a good bet.For more on choosing the right set of tyres, go to drive.com.au/tyre-tipsTYRE PRESSURE KEY TO LESS FUEL, BETTER SAFETYYOU don't have to buy a set of low rolling resistance tyres to save on fuel bills.Most tyremakers agree that simply keeping your tyres at the recommended pressure will reduce fuel consumption by between 3 per cent and 5 per cent.You'll also save money in the longer term because driving with flat tyres means more friction and stress and therefore wear on the rubber.Maintaining the right pressure is easier said than done, though.Air pressure should be taken when the tyres are cold; just driving the car to the petrol station can mean you get an inaccurate reading. And service station gauges can vary in their accuracy. It's best to overinflate a little to compensate, then check again later when the tyres have cooled using your own gauge.Improperly inflated tyres are dangerous, as well. The increased stress on an overinflated tyre can lead to blow-outs, while a car with underinflated tyres will take significantly longer to stop because all of the tread may not be in contact with the road. It also won't handle as sharply, especially in the wet.What next for old rubber?WHILE tyre companies are keen to spruik the environmental benefits of low rolling resistance tyres, they are less talkative about the impact of tyres on the planet.According to government figures, 52.5 million passenger tyres reached the end of their life in 2007-2008.Of those, almost two-thirds were sent to landfill, illegally dumped or stockpiled. Just 13 per cent of the total was recycled.The Department of the Environment, Water, Heritage and the Arts estimates if current trends continue, up to 680 million tyres will be sent to landfill over the next 20 years.At the release of the National Waste Policy in November, the federal government agreed to set up a "tyres round-table" aimed at reducing landfill and encouraging recycling.The first meeting is scheduled for next month and the government says it will explore ways to expand the market for products made from recycled tyres."Many opportunities exist for using end-of-life tyres including for road construction material and playgrounds. Flexible paints and glues are two other innovative uses," the government says in its National Waste Policy fact sheet.But the Australian government is lagging behind Europe on the issue. Europe has had a landfill ban on tyres since July 2006.In Britain, tyres are used for re-treads, alternative fuels, computer mouse mats, bookmarks, coasters and carpet underlay. Tyres are also reprocessed into chips for playing field surfaces and road drainage schemes

© 2010 Sydney Morning Herald

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