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A flat performance for run-flat tires

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A flat performance for run-flat tires

The standard complaints about run-flat tires that wear too quickly and offer an uncomfortable ride aren’t going away. In the last five years as the replacement rate of non-run-flat tires on two-year-old cars has improved by 4%, the run-flat replacement rate hasn’t budged an inch.

The annual survey by J.D. Power and Associates focuses on consumers who have replaced one or more tires during the first two years of new-car ownership. The replacement rate for run-flat tires is much higher than non-run-flats.

In 2011, the replacement rate for non-run-flat tires was 20%. It dropped to 16% in 2015. In that same timespan, the replacement rate for run-flat tires remained 27%.

“We’ve seen the replacement rate for non-run-flat tires improve over the last five years, but the replacement rate for run-flat tires has remained flat,” says Brent Gruber, who conducts the tire study and serves as director of the global automotive division for J.D. Power.

The faster-than-average replacement rates are problematic for tire manufacturers, especially as car makers force run-flats to take hold of a larger piece of the overall tire market. Car makers see run-flats as one answer to their ongoing efforts to reduce the weight of vehicles to meet new Corporate Average Fuel Economy (CAFE) standards by 2025.

In 2014, run-flats made up 1% of the replacement passenger tire market, with close to 2 million tires sold.

“It’s vital that auto and tire manufacturers address the ride and wear issues, which are still not meeting customer expectations,” Gruber says. “Customers expect that run-flat tires won’t compromise tread life or the ability to provide a quiet and comfortable ride.”

The complaints about tire ride are especially strong among what J.D. Power calls the performance sport car category, whereas the dissatisfaction with tire wear is most prevalent with luxury car owners.

There are other concerns, however. Consumer Reports recently highlighted the pain and suffering of one run-flat tire owner who got a flat tire while driving his dream car, a 2012 BMW 550i, on a long road trip. The car wasn’t equipped with a spare tire, and with damage to the sidewall, the owner was told not to drive on it. He waited on a flat-bed tow, spent a night in a hotel and was back on the road the next morning. Turns out this was the first of eight times his run-flats would go flat in less than 30,000 miles.

Extraordinary experiences like that one aside, the future of run-flat tires depends on improvements to ride and wear.

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So Modern Tire Dealer asked run-flat tire manufacturers about consumer complaints and how they’re going to improve their tires to satisfy both features.

Here’s who responded to our questions:

Marco Verzino, director of quality, and Steve Carpino, vice president of research and development for Pirelli Tire North America Inc.;

Lee Willard, tire engineer and Corvette tire specialist, Michelin North America Inc.;

Henry Kopacz, public relations and social media manager for Hankook Tire America Corp.;

Jay Robinson, general manager of brand marketing for Goodyear Tire & Rubber Co.;

Bob Liu, performance tires product manager for passenger and light truck tires at Continental Tire the Americas LLC; and

Robert Saul, director of consumer tire product strategy, Bridgestone Americas Tire Operations LLC.

Tire ride

Verzino and Carpino, Pirelli: The number of ride complaints on run-flat tires has dropped dramatically from the early days, when the ride was admittedly harsh/stiff. The tire companies have made the tires better for ride while maintaining the other required characteristics, while the vehicle manufacturers have gotten better at designing the suspension systems integrating the run-flat tire characteristics.

Willard, Michelin: Yes I’ve heard complaints on run-flat tire ride, but I’ve also heard more compliments on Michelin’s run-flat tire ride. Many consumers and even the OE test drivers that we work with can’t believe they are riding on a run-flat. Consumers interested in sporty handling almost never comment about comfort because they understand the relationship between ultimate handling control and comfort. Consumers only interested in a soft quiet ride should opt for standard radial tires to maximize these performances.

Vehicle manufacturers can greatly reduce the ride compromise when they apply technologies like magnetorheological (MR) shocks. These shocks make the chassis very soft for normal driving comfort and make the chassis hard for sport handling to best work with the sporty tuned tires, including run-flats.

An asymmetric run-flat design addresses both the comfort needs and grip needs of UHP run-flat tires. (Willard created and Michelin acquired a patent for a tire “having asymmetrical self-supporting sidewalls” in 2010.)

Kopacz, Hankook: In the area of ride performance, Hankook focuses on designing an optimal sidewall profile that provides the comfort consumers desire, while at the same time offering run-flat capability. Designers also focus on carcass structure and raw materials to provide comfortable ride characteristics.

Robinson, Goodyear: Goodyear is always looking for ways to further improve the performance of its products based on the needs of our consumers. This has led to significant advancements in the area of ride comfort with each new generation of our run-flat technology.

Today’s Goodyear RunOnFlat tire technology enables our tires to ride similar to a conventional tire when inflated, while still providing run-flat capability. This is especially true when the vehicle has been designed and tuned specifically for the use of run-flat tires.

Liu, Continental: We do get a few consumer complaints regarding ride comfort for run-flat tires. Run-flat tires have stronger construction than standard tires to be able to support the vehicle weight even without air pressure for limited distances. Stronger construction typically leads to a less comfortable ride. Through advanced engineering of new materials and contours along with careful tuning, the ride comfort of run-flat tires can be made to be close to standard tires.

Saul, Bridgestone: Many of the earlier generations of run-flat tires came out on sports cars where a firmer ride was more acceptable. We’ve worked really hard at Bridgestone to innovate new technologies that improve the ride comfort of run-flat tires.

Our third-generation run-flat technology, which is featured in the DriveGuard tire line, is specifically designed to improve ride comfort. We continue to hear feedback from consumers and dealers who say Bridgestone DriveGuard tires ride like a touring tire, while also delivering the safety and peace-of-mind that you can only get from a run-flat tire.

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Tire wear

Verzino and Carpino, Pirelli: We are improving tire wear like with any other tire: optimizing tire construction to target vehicle characteristics. The overwhelming majority of our run-flat tires are OE tires, therefore made to meet the target requirements of OEMs.

Willard, Michelin: Michelin tire engineers apply computer analysis tools to optimize contact patch for wear characteristics of run-flat tires. (See spider chart below for improvements to the run-flat tires on the 2016 Corvette Z06.)

Kopacz, Hankook: Hankook focuses on developing run flat tires with a more consistent footprint shape for improved tread wear.

Robinson, Goodyear: Goodyear has continued to refine its RunOnFlat technology since the company first pioneered the concept for commercial use more than 20 years ago. Our data today suggests the vast majority of consumers are satisfied with the wear rate of Goodyear RunOnFlat tires.

Liu, Continental: We continuously develop new technology for improving wear of all tires, including run-flats. Tread compounding, pattern design, contour shape and construction all have influence on wear.

Run-flat tires are not inherently different than standard tires except for construction, which affects comfort more than wear. The main reason run-flats do not have a great reputation for wear is that the vehicles with OE run-flats are typically tuned more for handling than wear.

Saul, Bridgestone: We know wear life is one of the top tire performance attributes that consumers want when they’re shopping for a new set of tires. We continually work across all of our product lines, including run-flat tires, to optimize our technologies and make sure that we deliver a tread wear performance that meets and exceeds the consumer’s expectations. Bridgestone’s new run-flat replacement tire line, DriveGuard, is backed by a 50,000 to 60,000 mileage tread wear warranty, which is improved over warranties on earlier generations of run-flat tires.

Marketing on safety

Despite their problems, the run-flat promise of not leaving a motorist stranded on the road is an effective selling point to consumers. Bridgestone’s DriveGuard tires have been on the market for a little over a year, and the tire maker says that’s been long enough to hear from consumers who are praising the safety factor. One consumer wrote the company saying she “never felt so confident about my safety with any other tire.”

Bridgestone is unique in its focus on consumers who want to shift from non-run-flat tires to run-flat products. Other manufacturers say the consumers asking about and buying their run-flat tires are ones replacing worn-out run-flat tires that came as OE.

“Most consumers purchasing our run-flat tires were satisfied with their OE run-flat tires and are purchasing replacements,” says Liu from Continental.

Potential for the future

Any growth of the run-flat market share is dependent on the car manufacturers. As their requests and fitments continue, the tire makers will follow.

“We are continually working with our OE customers to develop Goodyear RunOnFlat tires tuned to specific vehicle fitments where run-flat capability is desired,” says Robinson. “In general, we believe this market will continue to grow, especially in Europe.”

Pirelli says pressure to improve fuel economy and free up space inside the vehicle will continue to drive development, and “there may be an increase in the usage in run-flat products.” The company offers 14 tire lines and 175 run-flat tire products in the U.S. “This allows vehicle manufacturers to get rid of the spare tire and jack. BMW is a major player while Mercedes Benz is increasing usage of run-flat products.”

Petlas Tire Corp. is just entering the run-flat game. Caglar Bahadir is in charge of development for consumer tires for the Turkish tire manufacturer, and says the tire maker introduced its first run-flat tires during the third quarter of 2014 and is working to bring them to the United States.

“We are now into negotiations with several large size distributors from Tennessee, New York and Minnesota.” The company also plans to open an office in the U.S. “very soon.”

“We are expanding our run-flat tires portfolio. By the end of this year we will have 22 new tire sizes to meet our customers’ demands. We think the run-flat tire market will continue to grow,” Bahadir says. “As more and more manufacturers improve their suspension systems in order to accommodate run-flat tires, complaints of harsh riding experiences are being eliminated day by day. The safety and low fuel consumption run-flat tires offer seems to eliminate the concerns of high costs. The current increase in the run-flat tire sales globally is proof of this.”

Count Aeolus Tyre Co. Ltd. among the companies that’s investigated run-flat tire production. But Mike Leverington, general manager of Aeolus in the U.S., says run-flat tires have been, and remain, a top-tier tire product.

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“Run-flat technology tends to be found more with the Tier 1 brands and top Tier 2 brands, all of which have at least some OE position in the global passenger tire business,” Leverington says. “But the additional cost at retail, the limited number of miles that can be driven and the harsher ride criticisms have made the run-flat segment limited and more of a niche concept rather than a broad line segment.”

Those limitations make sales more difficult for lower tier tire manufacturers, Leverington says.

The big question

If run-flats are the tires of the future, just how long do consumers, and their tire dealers, have to wait until the tires ride and wear like the non-run-flats on the road today?

The answer is: It depends.

Some tire makers say they’ve already hit the mark. “Thanks to our third-generation run-flat technology, Bridgestone has run-flat tires on the market today that offer ride comfort and wear life that are comparable to conventional tires,” says Saul.

Even Gruber, the man who conducts the annual OE tire survey for J.D. Power, agrees. Their surveys show some tire manufacturers are getting high marks for ride or wear. J.D. Power just won’t share those brand-related findings because the manufacturers pay for that piece of the research. “As a total industry in the U.S. consumers place a great amount of emphasis on tire wear. Run-flat tire wear is an area where they are particularly deficient, particularly in the luxury vehicle segment,” Gruber says, “but there are some tire manufacturers who have optimized the run-flat tires to the point where those characteristics are not a deterrent, where satisfaction is comparable to non-run-flat tires.”

Pirelli says greater progress depends on the OE manufacturers and their expectations. “The shorter the distance the tire is expected to be capable of operating without air, the smoother the ride will become overall.”

At Continental, Liu says the problem is in the comparison.

“If you compare apples to apples, run-flat tires wear like traditional run-flat tires today,” he says. “If you compare an OE sport performance run-flat tire on a vehicle with its alignment tuned for handing, to a standard touring tire on a vehicle with its alignment tuned for wear, there is a big discrepancy.

“There will most likely always be a ride comfort disadvantage for run-flats due to the stronger construction, but the difference keeps getting smaller. Our latest run-flat tires have ride comfort that is approaching standard tires.”

With those stiffer sidewalls, Bahadir at Petlas says current run-flat tires won’t have the same comfort level as conventional tires. “But with developments by both tire and vehicle manufacturers, an average customer using run-flat tires on a vehicle designed for run-flats cannot distinguish the difference.”   ■

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