In the car world, the carbon-dioxide figures we often hear and read about are tailpipe emissions. But in reality, carbon dioxide is a byproduct of processes that begin with a vehicle's design and manufacture, then its operation and upkeep, and eventually its disposal. And that's actually true not just of the car as a whole, but also of its individual components.
During its presentation of the new Ecopia line in Thailand, Japanese tiremaker Bridgestone gave this breakdown of a tire's carbon-dioxide emissions throughout its lifespan:
* 8.3% from the procurement of raw materials;
* 2.6% from the design and production process;
* 0.5% from distribution;
* 87.6% from actual use; and
* 1% from disposal.
That percentage of emissions from actual use is equivalent to 263.4kg of carbon dioxide, and it really drives home the importance of producing rubber that is "fuel-efficient."
The Ecopia tires accomplish this mainly by having low rolling resistance, meaning there's less friction between the tire and the road so that a car's engine doesn't have to use more fuel to keep going. The two other hallmarks of the Ecopia tires are low rate of wear and reliable wet-weather performance.
Currently, however, the development of green technologies continues to bridge the gaps between efficiency, performance and comfort. For instance, it's not uncommon anymore for hybrids to provide a measure of driving enjoyment, and the latest diesels aren't the loud, shuddery things we've previously known. Eco tires, then, must also roll toward this direction of giving more than what's expected.
In the case of the new Ecopia EP200, which is designed for medium to large passenger cars, better handling performance is the added benefit. Its Ecopia II compound packs more silica and uses this higher silica content more efficiently via a heat-suppressing technology dubbed the Nano Pro-Tech.
This improves rolling resistance by 47.2% compared with the conventional Turanza AR10, but also compromises grip levels. To counter this, the "leaf block" pattern of the EP200's tread incorporates two features: reversed Z blocks of even stiffness to maintain stable contact with the ground, and high-angle lug grooves "that inhibit the deformation of blocks" through uniform distribution of energy. GUTT II simulation straight grooves reduce aquaplaning risks, while the high-stiffness shoulder blocks and the square shape of the tire's shoulder provide for stability and even wear.
Notably, the EP200 is an asymmetric tire whose inner sidewalls are stiffer than the outer ones. The purpose of this is to improve straight-line handling as well as cornering--but within the realm of daily driving conditions. "This is not a Potenza," Bridgestone's Japanese officers said repeatedly. As such, the EP200 can better carry out directional input as far as lane changes and normal turns are concerned. Sudden applications of full steering lock are a different matter.
All these elements of the EP200 lead to the following advantages over the Turanza AR10:
* An 8.1% increase in fuel efficiency;
* An 11.1% reduction in carbon-dioxide emissions; and
* A 3% improvement in wet braking.
The EP850, on the other hand, is the first eco tire specifically engineered for on-road CUVs and SUVs in the Asia-Pacific region. The prime considerations for it, aside from the usual Ecopia traits, are ride comfort and noise.
Its high-angle lug blocks promote even energy distribution to minimize deformation, while the rib-linked blocks contribute to low rolling resistance and uniform load bearing. Meanwhile, the 3D tread grooves ensure a comfortable ride, and the alternating short and narrow slots on the shoulders reduce the generated tire noise.
Overall, the EP850's rolling resistance coefficient betters that of the Dueler H/L683 by up to 20%, leading to improvements in fuel efficiency and carbon-dioxide emissions of 3.9% and 3%, respectively. Its wet-braking characteristics also beat that of the conventional tire by 4%.
Of course, no matter how promising these figures are on paper and no matter how well the tires do on short handling test courses, it's really over the long run that these new Ecopia models must be assessed. And we hear that Philippine Allied Enterprises Corporation, our local Bridgestone distributor, has an Ecopia test-drive event planned for later this year, so we'll see then just how much these green tires have evolved.
Photos by Sharleen Banzon and Bridgestone