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Green Tires Reduce Rolling Resistance

Published Mar 3rd 2008, 9:26pm by Jody DeVere in Featured Articles

Car tires can play a role in improving our gas mileage – and regulators are starting to realize that. Tire makers are finding their industry being subjected to increasing regulations in reducing the rolling resistance of tires. One approach to achieve this is by reducing tire thread thickness to reduce rolling resistance. This regulatory approach will take some pressure off car manufacturers to shoulder the whole burden of efficiency improvements. However, there are technical challenges in that a thinner tread can weaken a tire’s traction or its life span, resulting in more used tire scrap.

What’s the science behind rolling resistance? We all know that a standard way to improve the miles-per-gallon you can get out of your vehicle is to keep the tires properly inflated. This allows the tire to assume a more round shape, which means less surface touches the road. By basic physics law, friction causes resistance. That’s how a tire maintains its grip on the road and how a brake successfully stops a car. However a vehicle’s weight compresses the tire – causing the engine to work hard to roll the car forward. About 20% of your car’s energy is used to work the tires, according to a recent article in the . Proper tire pressure will combat some of this compression thus less gasoline is needed.

In addition, a thinner thread (that is the size of the rubber tire relative to the size of the rim) will also reduce rolling resistance, because the same tire pressure needs to work on a smaller amount of rubber to push it outward. Of course the tire is a lighter too with less material. The drawback is that a thinner thread could be weaker. However, this seems like a technical design and manufacturing challenge that can be solved as long as manufacturers have the incentive or need to do so.

I first came across this issue while reading news releases about Yokohama’s new tires. It is not an area that has received much coverage in the press, but is starting to do so. One company stood out for me, as I did my tire research (an interesting way to start my day indeed). I have become quite impressed with Yokohama Tire’s track record on the environment.

It seems that Yokohama Rubber Company is quite active in green technology R&D, not just in improving the environmental impact of using its end products – tires, but also in how these products are built. Its Environmentally Conscious Designs initiative seeks to help combat global warming through increased resource recycling, reduced energy consumption in manufacturing, while still improving products safety and comfort. Reusing recycled products for manufacturing, also called “closed-loop manufacturing”, is increasingly popular in our increasingly resource constrained world. Yokohama, for example, is currently working on a “dream rubber” which can be recycled repeatedly. In fact, in Jan 2007, they established a mass production technology of using waste of vulcanized rubber as a raw material for new tires and began their first internal mass production using recycled rubber, a first for the tire industry. The plan is to use 400 tons of recycled rubber for the production of new tires (while maintaining high quality). This effort will divert a similar amount from landfill, and helps combat rising material cost.

In addition, they also looked into the sustainability of materials used in manufacturing. Some tires now use something called the “Super Nanorubber” (great name isn’t it?), made from citrus oil (from the skin of oranges) and nanotechnology for its new material inner liner composed of a micro compound of rubber and plastic. As a result, the rate of non-petrochemical resources was increased to 80%.

In addition, in Apr 2006 they achieved complete zero emissions a year earlier than planned, and in Oct 2006, obtained the top level environmental rating from the Development Bank of Japan. To promote their green image, and to reach more people to adopt sustainable lifestyle, they host a green social networking site, which offers daily green news and forums, “how to” guides, and interviews with musicians.

Looking back in history, Yokohama has a history of innovation in end-user product.
• In 1937, “Y-type Tire” improved the durability by adopting new tire cord materials.
• In 1967, the “GT special” became the first radial tire brand in Japan.
• In 1978 the“ADVAN” was created -- a super high grip radial tire.
• In 1982 the“ASPEC” was created, with emphasis on ride comfort and silence
• In 1998, e-Spec “DNA” brand was release instilled with their latest environmental technology

Sustainability is the next wave of innovation for companies around the world, to create more shareholder and stakeholder values. It seems to me that Yokohama has its heart in the right place and follows it up with actual results that continuously improve their track record as a responsible company. One thing my MBA education is helping me realize is that if a truly sustainable company is one that is eco-friendly in all aspects of its operations. This usually shows up as: (a) a commitment to environmentally friendly design, (b) operational improvements that reduces eco-footprint, and (c) actual eco-friendly products that consumers can buy in the marketplace. Many companies are moving in this direction, but I am finding, rather surprisingly and pleasantly, that Yokohama seems to already be there. It is great to discover another item in my daily life that can be more eco-friendly.

How can we save money while doing some good for the environment at the next tire change? I will explore this in the next blog.

Marn-Yee Lee
Contributing Editor

Marn-Yee Lee is pursuing an MBA in Sustainability at the Presidio School of Management in San Francisco. After spending a decade in I.T. and on Wall Street, she is now pursuing her passion for the environment. She sees business as a partner for creating innovative solutions to pressing environmental issues. In her spare time, she writes a blog to inspire others to consider the impact of their daily lives on the environment at .

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