Tire Weight Reduction in Passenger Cars and Light Trucks – Which Companies are Driving the Technology?

By Ben Bahavar, Ph.D., Nerac Analyst

Originally Published June 14, 2016

Introduction

In the automotive sector – including cars, light trucks, and motorcycles – as well as the commercial aerospace industry, lightweight materials increasingly replace metal parts or structures, thus enabling manufacturers (OEMs) to meet ever stricter regulations to reduce fuel consumption and CO2 emissions of their vehicles. Over the past few years there has been an increase in patent and non-patent activity concerning the development of new grades of engineering polymers as materials to replace some of the metal components in automobiles and airplanes.

Innovation has also picked up pace recently with new micro-alloyed steel compositions that could lead to lighter metals with high strength for use in structural components – this is due to the demand for decrease in the thickness and increase in the strength of structural parts for automobiles out of consideration of global environmental problems and collision safety.

For lightweighting in the automotive sector, a great majority of innovation concerns new grades of engineering plastics – the intended applications being for under-the-hood parts (oil pans, encapsulants to reduce engine noise & vibration, etc.) and exterior & interior components (bumpers, instrument & door panels, seats, sealing strips for vehicle windows, etc.). Comparatively, very little discussion is found in the open literature concerning lightweighting in tires.

Light-weight or Reduced-weight Tires

In a March, 2016 interview by Just-Auto Global News, Pirelli Tyre’s Head of Marketing and Supply Chain Matteo Battaini commented on the question “what premium will OEMs pay for weight reduction?” He indicated that there is continuous research in terms of materials, and that achieving lightweighting used to be at odds with better tire performance and rolling resistance. But today, it is possible to achieve all three because of the emergence of new materials and polymers. Battaini indicated that weight reduction is an important element to reduce rolling resistance and improve fuel consumption. “What they [OEMs] are paying for is new technology that helps the carmaker to reduce the weight of the car, transferring to the tyres some other solution. For example, our P Zero system features a noise cancelling system inside the tyre that, in turn, enables OEMs to reduce the weight of the car by eliminating other noise cancelling parts, such as the rubber beams on the suspension.”

The focus of this article is on innovation as represented by patent activity over the past 10-15 years in development of lightweight tires. With an emphasis on passenger car tires as opposed to aircraft tires, bicycles, motorcycles, or golf carts, we have identified the following companies as the major players in driving the innovation as evidenced by published patent applications and granted patents:

• Bridgestone Corp. (& Kuraray)
• Sumitomo Rubber Industries
• Yokohama Rubber Co. Ltd. (& Honda)
• Kolon Industries Inc.
• Michelin
• Goodyear Tire & Rubber
• Dow Global Technologies
• MKP Structural Design Associates, Inc. (Dexter, Michigan)
• Pirelli SpA
• GM Global Technology Operations Inc.
• Hankook Tire Co. Ltd. (Korea)
• Mitsubishi Gas Chemical Co. Ltd.
• Toyo Tire & Rubber Co.

A total of 72 patent families (2000-2016) are assigned to the above companies. This collection represents 437 patent applications, 204 granted patents, and 17 patent authorities (jurisdictions worldwide). As depicted in the following snapshot, the highest level of patent activity occurred over the past 3-4 years representing about half the total patent activity since 2000.

It is important to note that a patent family contains several patent records (documents, members) published as patent application(s) or granted patent(s) under one or more patent authorities (US, EP, WO/PCT, JP, CN, GB, etc.). Also, a patent family as a whole may address more than one aspect of a unique invention (method/process, composition of matter, apparatus, etc.). Thus, different members may have different titles, abstracts and set of claims.

Key or major patenting authorities are defined as US, EP, and WO/PCT – each of the 72 patent families collected for this article have at least one member (patent application or granted patent) under US, EP, or WO. By design, here we did not consider any patent activity that did not have a member under US, EP, or WO – almost all major inventions will have a member under at least one of these three major patent authorities. As indicated above, 17 patenting authorities are represented in the dataset for this article – the following are the remaining 14 patent authorities: JP, CN, DE, KR, RU, IN, ES, FR, BR, AT, AU, TH, MX, and CA.

The following graph depicts 189 out of the 204 granted patents present in the dataset:

The company breakdown for the 72 patent families is shown below:

A quick comparison of the above two graphics point out marked differences in the ranking of patent assignees. For instance, although Dow Global Technologies is assigned only one patent family, it has 10 granted patents within that one patent family.

In-depth Analysis

A major part of Nerac’s patent analysis involves customer-defined parameters for a more in-depth examination of patent activity and trend analysis. For this article (tire weight reduction), we have categorized all 72 patent families according to the following 8 sub-topics:

• Rolling Resistance
• Composite
• Run-Flat Tire
• Steel Cord / Belt
• Composition Claim
• Method Claim
• Apparatus Claim
• OTHER

The following screen-shot depicts the foundational patent dataset that can be utilized for trend analysis, queries and answers via graphics and/or by simply using the filtering features in the Excel spreadsheet. Columns D through K represent the above 8 sub-topics.

Patent families in this screen-shot are ranked based on the number of forward citations (column “N”). It is generally accepted that an invention is more unique/novel if it has a higher number of forward citations and a lower number of backward citations. This statement cannot be applied to the newly published patent activity since it will usually take a few months/years for the forward citations to be noted in patent search platforms.

Based on the volume of patent activity as well as the coverage of the 8 sub-topics chosen for this article, it is evident that Bridgestone, Sumitomo Rubber Industries, and Yokohama Rubber Co. are the top drivers of the technologies to reduce tire weight for passenger cars and light trucks. The first sub-topic, rolling resistance, has always been the main performance attribute in tires. The top companies focusing on this parameter appear to be Bridgestone, Sumitomo Rubber Industries, and Michelin. The overall leader is clearly shown to be Bridgestone.

The above graphics are included for illustrative purposes on the focus of this article: the companies that are major drivers of technology in reduced weight tires in passenger cars. Clearly, the foundational dataset (the Excel spreadsheet) lends itself to unlimited queries and trending graphics.