Run-flats: what a difference a decade makes

Bob Bissler
Posted on August 19, 2014
Nokian Tyres offers the Flat Run line of run-flat tires for both passenger and SUV vehicles. The Hakkapeliitta 8 winter tire (pictured) also features run-flat technology
Nokian Tyres offers the Flat Run line of run-flat tires for both passenger and SUV vehicles. The Hakkapeliitta 8 winter tire (pictured) also features run-flat technology

There seems to be love and hate relationships when it comes to run-flat tires (RFT). Auto manufacturers love offering the selling point of better fuel economy due to the lighter vehicle weight that run-flats offer by eliminating a spare tire. Consumers hate the high cost to replace original equipment run-flats and are struggling with their comfort level. Tire makers are caught in the middle.

We asked manufacturers to share their run-flat knowledge with us. There were 2 million replacement run-flats shipped in the United States in 2013 and 1 million OE run-flats. Manufacturers expect both numbers to increase in 2014.

While the number of OE run-flat fitments continues to rise, primarily on luxury vehicles, some tire makers are targeting the replacement market with more affordable run-flat options.

What does the future hold for run-flat technology in the U.S.?

MTD: How has run-flat technology evolved over the last 10 years?

Michael Mathis, president, Atturo Tire Corp.: The evolution has been quite gradual. We have taken advantage of the ability to support a larger SUV with our RFT AZ850. In general, run-flat technology has evolved to be applied to a wider range of sizes, particularly low-profile performance tires.

Robert Saul, senior product manager, Bridgestone Americas Tire Operations: We’ve focused our efforts on improving ride comfort in our latest generation of run-flat tires. In our newest run-flat offering, DriveGuard, we’ve used 3rd Generation, or 3G Run-Flat, technology to deliver a quiet, comfortable ride and confident handling of a touring tire. Bridgestone’s proprietary technologies, including our Cooling Fin sidewall design and NanoProTech sidewall reinforcement rubber compounds, have enabled us to make significant improvements over prior-generation run-flat tires.

Goodyear Tire & Rubber Co.: Self-supporting tire technology has evolved quite a bit over the past 10 years. Goodyear has a third-generation product that offers inflated ride comfort while still providing zero pressure capability. The concepts of yesterday and today are generally the same, but with a more refined balance between inflated and deflated performance.

Henry Kopacz, public relations manager, Hankook Tire America Corp.: Run-flat tires have evolved over the past number of years. New run-flat tire technology can be used to develop tires that do not sacrifice ride or comfort, a limiting factor for some consumers in the past.

Ron Margadonna, senior technical marketing manager, Michelin North America Inc.: With Michelin run-flat tires, we have strived to engineer our product with less mass for improved rolling resistance to meet tougher Corporate Average Fuel Economy (CAFE) standards without compromising any safety mobility performance. Also, we have generated a newer-type technology called ZP SR (Zero Pressure Short Range) to further enhance and meet OEM requirements.

Steve Bourassa, passenger and light truck products manager, Nokian Tyres Inc.: The reinforced sidewall concept, or self-supporting structure, of run-flat tires has remained essentially unchanged for over 10 years. Nokian continues to improve the comfort and rolling resistance of run-flat tires, despite how the weight of the tire and rigidity of the sidewalls work against these aspects of tire performance.

Steve Carpino, vice president of research and development, NAFTA, Pirelli Tire North America Inc.: In 2004, the run-flat concept was still very new. Back then, we had only one size in run-flat, the 205/45R17 for the BMW Mini. In 2004, only BMW was looking seriously at large-scale use of run-flats and designing their vehicle suspension systems around the concept. With those early run-flats, the internal  structure of the  tire provided a comfort ride level that would not be acceptable today.

In 2014, with a decade of research and development under our belts, we can adjust the tire design and sidewall thickness to get a high comfort level to match what OEMs are asking for while maintaining performance requirements and the run-flat mileage required. In most cases the typical consumer will not be able to tell they are driving on run-flat tires.

Maxwell Wee, director of sales, Sentury Tire Americas: The original idea for RFT was to provide extended mobility to vehicle operators. While this has not changed, other factors have come into consideration in response to consumer demand. The latest RFT tires have to provide extended utility while maintaining the comfort level of a regular tire. Manufacturers have responded with new sidewall and compounding technology that will do both. RFT tires are now available for applications on vehicles without the need for a special suspension setup.

Bob Abram, product planning manager, Yokohama Tire Corp.: The primary challenges on run-flat tires initially were price, harsh ride quality and, due to the fact that many of the original run-flat tires were summer UHP products, tread life. All of those issues have been addressed to some degree in the past 10 years, but probably not to the degree of ultimate customer satisfaction.

MTD: What run-flat tires do you market?

Mathis, Atturo: We have just launched the AZ850 performance tire for SUV, crossover and sport trucks. We have included four run-flat sizes of 19- and 20-inch and expect to add more.

Saul, Bridgestone: Our newest run-flat tire, the Bridgestone DriveGuard, is the industry’s first full line of run-flat tires designed for use on vehicles not originally equipped with run-flat tires. Available in 32 sizes to fit a wide assortment of today’s popular sedans, coupes and wagons, DriveGuard is backed by a 60,000-mile (H- and V-rated) or 50,000-mile (W-rated) limited tread wear warranty. An all-season tire, DriveGuard delivers everyday performance similar to other popular conventional tires on the market with the added benefit of zero pressure mobility (distances up to 50 miles at speeds up to 50 mph).

Mauricio Mendez Sotelo, manager, Technical Product Specialist R&D, Continental Tire The Americas LLC: Our Self-Supporting Run-flat (SSR) technology is available in some sizes of the following product lines: Conti-SportContact 5, ContiSportContact 5P, ContiProContact, ContiWinterContact TS810S, ProContact GX, CrossContact UHP, 4x4 Contact and CrossContact LX Sport. The SSR principle is based on a reinforced self-supporting sidewall. This prevents the inside of the tire from getting pinched between the road and the rim and from slipping into the rim well in the event of a loss of inflation. The SSR’s reinforced sidewall enables the car to continue on its way at a maximum speed of 50 mph for up to 50 miles, depending on road conditions and vehicle weight.

Goodyear: Goodyear markets many run-flat products in various tire lines, including summer, all-season and winter. We offer ultra-high performance and performance run-flat tires. Some of Goodyear’s run-flat tires include Eagle F1 Supercar, Eagle F1 Asymmetric 2, Eagle RS-A, Eagle LS-2, and others.

Kopacz, Hankook: Hankook currently provides OE run-flat tires for Mercedes-Benz and Mini. Low rolling resistance is one of the main performance targets for these tires, as it is for our other patterns whether passenger, light truck or truck and bus.

Margadonna, Michelin: Michelin markets run-flat tires that are named ZP (Zero Pressure). We are unique in the sense that ZP is a technology that is offered across several tire lines. We develop a particular tire line/size working with the OEM such as Corvette where the Michelin Pilot Super Sport ZP is the OE tire. Michelin does not manufacture a dedicated tire line entirely with ZP.

Bourassa, Nokian: Nokian Tyres offers Flat Run tires for aftermarket sales, available for both passenger and SUV vehicles. The most popular Nokian tires with run-flat technology are Hakkapeliitta winter tires, although run-flat products are also available in summer patterns and all-weather WR models.

Steve Ewing, NAFTA product manager, Pirelli: We produce run-flat versions of select sizes in many of our lines.

Wee, Sentury: Our RFT tires are available in popular OE replacement sizes and feature specially designed sidewall construction and compounds to enhance ride comfort and noise reduction.

Abram, Yokohama: Yokohama offers two run-flat treads. The Advan Sport ZPS is a summer tire based on our Advan Sport design, and perfect for replacement on high-performance or luxury coupes and sedans from Europe and Asia. The Avid ENVigor ZPS is a tire that addresses the issues of ride quality, price and tread wear. We use a special insert in the sidewall area to keep the high-performance feel and safety of operation at zero air pressure levels, but still allow for a more comfortable ride. We also use a compound that still provides confident grip but also provides better wear than many OE products, and a price that provides great value.

MTD: On what vehicles are your run-flat tires designed to be used?

Mathis, Atturo: Our primary application is BMW X-series.

Saul, Bridgestone: Bridgestone’s original equipment run-flat tires are designed for use on the specific models they are fitted on from the factory. Our run-flat tires are OE options on many vehicle makes, including BMW, Toyota, Lexus, Cadillac, Infiniti, Mini Cooper, Nissan and others. We also offer many run-flat tires designed for use as replacement market alternatives. What makes DriveGuard so different is that it is designed for use on a wide variety of newer sedans, coupes and wagons not originally equipped with run-flat tires. The main requirement is that the vehicle must have a functioning tire pressure monitoring system to alert the driver in case of a loss of pressure.

Mendez Sotelo, Continental: Our run-flat tires are designed to be used on vehicles that are originally fitted with SSR technology. Our SSR technology is available on some BMW, Mercedes-Benz and Audi fitments.

Goodyear: Most of our run-flat products are designed for luxury coupes, sedans and luxury SUV/CUVs.

Kopacz, Hankook: Hankook’s original equipment run-flat tires are fitted to the BMW 3 Series, Mini Cooper and Mercedes-Benz C-class.

Margadonna, Michelin: Michelin ZP tires can be fitted to all Michelin tires that are OE on many OEM vehicles as well as many ZP sizes that have been created as replacement size offerings to other vehicles with run-flat tires.

Bourassa, Nokian: We produce run-flat tires that can be equipped on many BMW, Mini and Mercedes-Benz vehicles; in addition to Cadillac ATS, Infiniti Q50, Mazda MX-5 and Toyota Sienna.

Ewing, Pirelli: Our run-flats are designed for individual OEM applications. We currently produce run-flat sizes for the Audi TT, most of the BMWs, Cadillac CTS, Jeep Grand Cherokee STR8, the Mercedes-Benz A, B, C and S Classes, CLA, ML, and SL, the Mini Countryman, Cooper and Paceman, and the Volvo S80 and V70. That said, there is nothing stopping a consumer from using a run-flat SKU on a different application than those they were designed for. I’m personally using our 225/45R17H Cinturato P7 All-Season run-flat designed for the Mercedes-Benz CLA on my Volkswagen Jetta and the tire feels great.

Wee, Sentury: Mini Cooper, BMW 1, 3, 5 and X5 series, and Mercedes-Benz C and E class.

MTD: Will run-flats ever become mainstream tires in the U.S. replacement market?

Saul, Bridgestone: We believe that day is here thanks to the introduction of our DriveGuard tire line. This technology, once reserved for premium sports cars and sedans, now is available for millions of drivers of popular cars such as Camry, Accord, Corolla, Fusion and others.

Goodyear: We do see the market growing, but not to levels that would make the technology standard equipment on all cars.

Kopacz, Hankook: We expect the run-flat segment to grow in the United States in the future.

Margadonna, Michelin: It is difficult to say. It will depend primarily on what the OEM outlook is. From our research, we find consumers are delighted with the safety mobility aspect, but are surprised at the expense when they need replaced. It may take considerable time for run-flat tires to reach large mass appeal in the marketplace.

Ewing, Pirelli: I believe run-flats will become much more mainstream in the U.S. replacement market. They are a win-win for OEMs and consumers. For OEMs, not needing to have a spare tire lowers the weight of the vehicle, increasing fuel economy. This will become more and more important as CAFE standards increase. For the consumer, there is also added safety and peace of mind. Not having to change a flat on the side of the highway is a big selling point.

Wee, Sentury: The key will be the manufacturer’s ability to bring construction costs down to a level where the tires can be priced at the mainstream level without hurting quality and ride comfort. The potential is there, as the extended utility that these tires provide just makes too much sense.

Abram, Yokohama: It’s a possibility, but in order for that to happen, it would take a serious consumer education initiative, increased auto manufacturer adoption and increased industry production capacities. We believe it will be a challenge for all of these elements to align anytime soon.    ■

Related Topics: Atturo Tire Corp., Bridgestone Americas Tire Operations, Continental Tire the Americas LLC, Goodyear Tire & Rubber Co., Hankook Tire America Corp., Michelin North America Inc., Nokian Tyres Inc., Pirelli Tire North America, Run-Flat Tires, Sentury Tire Americas, Yokohama Tire Corp.

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Bob Ulrich was named Modern Tire Dealer editor in August 2000. He joined the magazine in 1985 as assistant editor, and has been responsible for gathering statistical information for MTD's "Facts Issue" since 1993.
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