Many people think of tires as singular objects, but they actually are made up of different components, compounds and materials – each of which performs a specific task as it rolls down the road.
You can be forgiven for thinking that building truck tires involves a bit of alchemy. The process by which tires are created – the delicate art of forming, combining and curing raw materials like rubber, steel, carbon black and graphite into tough, dependable and efficient tires – has evolved slowly but steadily since Charles Goodyear first vulcanized rubber way back in 1843.
“Normally, you’ve got about 14 different components in that tire,” says Guy Walenga, engineering director of commercial products and technology for Bridgestone-Firestone North American Tire. “And all that rubber has to stick to all that steel. And all that steel has to be insulated in such a way that doesn’t allow it to touch any other steel.”
Why so much trouble? For starters, consider the length of time a tire is expected to be on the job. The tire revolves, on average, about 500 times in order to travel one mile, and a truck might run 400 to 500 miles a day in on-highway operations for 300,000 to 400,000 miles or more. During each revolution, each of the 2,000 body-ply cables deflect inside that tire, generating heat and wear on their surrounding components.
And, of course, these aren’t miles run in a test lab. They endure variations and extremes of weather, temperature, inflation and terrain. And there are potholes, curbs and road debris.
How tough is the environment? “In the late ’80s and early ’90s, we were looking at installing internal electronic tire tags to measure pressure, developing the tags,” Walenga says. “We were trying to put an electronic device with a battery into the tire, and we found out where we were trying to install these components in – the inside air chamber of a tire – was a more hostile environment than outer space, thanks to intense temperature changes and constant G-loads.”
If the challenge of durability and reliability wasn’t enough, over-the-road fleet operations have become more intensely focused on fuel economy in recent years. But features such as lower rolling resistance typically aren’t those that promote longevity. Helping fleet owners achieve these important – but often conflicting – goals involves considerable ingenuity in design, materials and technology to build tires for more narrowly defined applications.
Figuring on fuel
There is good news – and bad – when looking at the future of tires. The good news is that very soon, tires will last longer than ever. The bad news is that you’re going to pay more for them. “Raw material costs today in the tire industry are at an all-time high,” says Shaun Uys, director of NAFTA replacement truck tire sales for Continential Tire North America. “The increases year on year are so large that they cannot be completely offset within the operational business of the tire manufacturers – this will force tire manufacturers to pass at least some of these costs on to the fleets.”
Tires are, indeed, getting better, though you might not notice from year to year. “Tire design tends to be more evolutionary than revolutionary,” says Tim Miller, marketing communications manager of commercial tires for Goodyear. Revolutionary advances in tire development have been few and far between. There was the development of the tubeless tires in 1947 and radial tires in 1948. But beyond that, tire technology advancements largely have been incremental. And like any market, tire OEMs respond as quickly as possible to the latest trends – which, according to Miller, now has brought fuel efficiency to the forefront of tire technology.
“We have multilple design focal points for future tires,” Miller says. “Fuel economy has bubbled to the top in recent months as a primary concern. But tires do many different things for a fleet operation. So we can’t take our eyes off the need for extending tread life, resisting irregular wear, improving casing durability and self-sealing tires.”
“Your future starts in the past,” says Don Baldwin, product marketing manager for Michelin North America. “We were all about fuel before fuel was cool by pushing the envelope with low rolling-resistance technology for the past 20 or 30 years. And if we had not done that, it would really be too late to get a jump on fuel efficiency because the construction and materials used in truck tires are way too sophisticated and technical to start from scratch today.”
For Baldwin, any talk of future tire technology doesn’t center only on the materials that go into tires or how they’re built. He insists that different tire types and new approaches to old tire applications are equally important. “Reducing tire weight and rolling resistance is the best way we know to boost fuel economy. The logical next step was to get rid of a couple of sidewalls. And that’s why we went to the wide-based single drive tire.”
Baldwin says the wide-based single tire has the benefits of low weight, which translates into additional payload for fleets. “There’s always a tradeoff when you’re looking at fuel economy and additional payload,” he says. If fuel only costs $2 a gallon, then it’s not that big of a deal, but when fuel costs $4.50 a gallon, the benefits are 10-to-1 in terms of fuel savings, he says. “Our X-One wide-based single is now working on logging fleets in the Pacific Northwest. It’s not only helping those fleets carry a few more logs, but it’s improved their traction, and fuel economy has gone up by 5 to 7 percent – which is huge.”
Tire makers are trying to tackle conflicting challenges not only in design and basic materials but in the very process of building the tire. Hankook Tire America, for example, recently introduced a new mixing system aimed at establishing both durability and fuel economy. The process reinforces a stronger bond between materials in the tire and generates lower heat, both characteristics that improve tire life, says Brian Sheehey, Hankook’s commercial tires director.
“We’ve combined that with a unique coupling groove which maximizes tread wear on our new AL07+ tire,” he says. “This new groove helps decrease the amount of heat generated on the road and makes the tire less susceptible to tearing.” To ensure even wear characteristics, Sheehey says Hankook developed its new Control Contour Technology, which is intended to allow the internal force on the carcass to be distributed evenly around the tire to prevent concentrations in one specific point. “Not only does this aid tire durability, this feature also helps extend the ability for retreading.”
But as tires evolve, manufacturers constantly have to deliver the capability and durability as measured by traditional expectations, Walenga says. “You can’t give any of that up as you work to increase fuel economy or improve rolling resistance – that’s the challenge we face.”
The task would be tough enough if tire makers focused only on one application. But tires that deliver excellent fuel economy and low rolling resistance while excelling in regional or linehaul, pickup-and-delivery or vocational applications have different real-world requirements in terms of casings, traction and durability.
“We’ve always developed tires for different applications, and in the future I think you’ll see more tires come on the market specifically designed for more unique applications,” Walenga says. “Doing so enables OEMs to design and build tires that work better given the narrower parameters they’ll perform while delivering better fuel economy and reduced rolling resistance. By subdividing tires into these groups, it makes it easier for us to meet some of these lofty goals. But it puts more tires on the market and makes choosing the proper tire more difficult for a fleet manager.”
Tougher compounds, less tread depth
Aside from some experimentation with Kevlar and other synthetic fibers, don’t expect to see major near-term changes in the fundamental compounds that have been used in highway tires for many years. But there are some significant refinements in progress. And for Baldwin, nothing illustrates the changes in how materials will change in the future better than steer tires, since many new approaches are being applied on them first.
“In the past, you’d get additional tire life with deeper tread depths,” Baldwin says. “That was the mantra. But deeper treads mean a heavier tire and one that delivers less fuel economy.”
But now, Michelin is experimenting with new ultra-high-strength tensile steels and more robust compounds that allow the construction of lighter tires with more elegant – and shallower – tread designs. “Tread depths are going to go down,” Baldwin says. “That’s a trend you can count on.” Currently, where new tires with tread depths of 30/32 or 32/32 are the norm, depths of 20/32 or even 19/32 may dominate in 10 years, he says. “And these tires will be made of tougher compounds that will allow them to go 50 percent farther then tires today, wearing less over time and delivering better fuel economy.”
“Compounds are the real black art of tire development,” Walenga says. “They affect rolling resistance, traction, its appearance and especially how the steel and rubber bond together and stay bonded together.”
In fact, as tire makers find compounds that allow them to design longer-lasting tires, they have run into some unforeseen problems related directly to the types of compounds used in them. “We found out that as a tire ages, and as they last longer, their appearance changes,” Walenga says. “Tires age to some degree – a tire that is six or seven years old gets ozone cracking down its sides. The tire is still good, but that natural cracking leads managers to decide it’s about to fail.” Compounds that make tires look visually appealing even after 750,000 miles would inspire confidence, he says. “If you look at it and don’t like the way it looks, you’re not going to care that it’s got new tread on it. You’re going to take it off the truck and put another tire on in its place.”
Pros and cons of smart tires
Miller says that all tire manufacturers currently are experimenting with “smart” tires – usually electronic sensors mounted in a patch inside a tire capable of transmitting crucial data about that tire’s health to a fleet manager. “The costs for this type of technology continue to keep coming down,” he says. “It’s only a matter of time before these systems go from experimental to commonplace.”
Tire tagging was pioneered on large off-highway earthmoving trucks – a natural place to begin, Baldwin says. “On earthmover tires, you’ve got a lot of space where you can put a patch with an electronic device in there,” he says. “In truck tires, you don’t have as much space. Things have to be smaller, and you have to be a bit more elegant. But you’re still going to see more and more in the way of electronics and chips installed – not only in a patch inside the tire, but also in the structure of the tire itself.”
At the first level, the chips will provide fleets with identification information so they can track the casing through retreading and make sure they’re comfortable with that process and know exactly how many lives the tire has been through. “Ultimately, it also can deliver information such as pressure and temperature, and even measure how the rubber itself is performing throughout the life of the tire so that we can project how long the tire is going to last,” Baldwin says.
Walenga remains unconvinced. “The worst place on a truck, in terms of tire maintenance, is the trailer,” he says. “And the one place where you now have pretty good onboard systems available to maintain tire pressure is on the trailers. Those systems are becoming more commonplace, so I think that problem is being successfully addressed.”
But Walenga isn’t certain that electronic systems make sense on tractors. “I’ll support any system as long as there’s a demonstrated benefit and a return on investment for the end user,” he says. “But the costs would have to be subsidized early on because it’s just that expensive to get these programs down to a point where fleets can afford them.” The infrastructure is a significant cost, he says. “You’re going to need to get a lot of readers or gauge systems, and suddenly you’re talking about a lot of costs that people didn’t see in the beginning because they just wanted a tag to check air pressure so they wouldn’t have to do deep-knee bends every morning.” Other factors – such as lack of standardization and the hostile environment inside tires – also will have to be surmounted, Walenga says. But the biggest obstacle, he says, is the lack of a viable software program to support any electronic tire maintenance system in a real-world environment.
No matter how slowly advancements in tire technology proceed over the next several years, they will change the way fleets buy, use, retread and dispose of tires. “The price of raw materials is going up, whether we’re talking about fuel and oil or natural rubber, carbon black or silica,” Baldwin says. “And if we can achieve the same or better results in terms or wear life, durability and fuel economy with less materials, that’s great for everybody because dinosaurs aren’t dying anymore. That’s a lot of what our research is about – how do we do more with less.”
Keeping them rolling
YRC Worldwide finds self-sealing tires to be promising
As a veteran manager of vehicle maintenance, Don Pabst is looking specifically at tire technology to accomplish one thing – eliminate unscheduled enroute tire-related downtime.
“We need to have a tire that can be replaced on a schedule instead of a tire having to be replaced due to failure,” says Pabst, vice president of maintenance for Overland Park, Kan.-based YRC Worldwide. Based on analysis and industry figures, tire failures are a leading cause of enroute delays. The intense heat generated by running tires with low air pressure causes the majority of all tire failures.
Enroute tire failures can cost a minimum of $500, not including the cost of a delayed driver and customer’s product. Depending on the severity of the failure, the tire casing may not be reusable for capping – another $80 cost.
Tire technology that maintains proper inflation and allows the tire to keep rolling until a scheduled repair is completed could eliminate many enroute delays and improve public safety by reducing the number of disabled trucks on the highways due to tire-related issues. Reducing the number of underinflated tires also would improve fuel economy.
For years, many fleets have tried to reduce tire failures by using aftermarket liquid-based tire sealants added to the tire chamber to prevent air loss due to punctures. But these sealants can be messy and inconvenient – and potentially shorten tire casing life. Automatic tire inflation systems are another option, although they require a capital investment as well as ongoing maintenance.
Early this year, YRC Worldwide began testing a new self-sealing trailer tire from Goodyear – the Unisteel G316 with DuraSeal technology. This tire technology uses a self-sealing gel-like compound under the tire tread to stop air leaks caused by nails and other punctures.
YRC Worldwide placed 1,000 DuraSeal tires in service on a new group of trailers. For the control evaluation group, the company used new trailer tires from a separate tire manufacturer. To date, the technology looks promising.
“Although it is too early to draw conclusions, we can safely say at this point that the DuraSeal appears to have reduced enroute tire delays significantly,” Pabst says. “As we continue this evaluation, time will tell if this very positive trend continues.”
As the company continues to evaluate the new technology, another critical data point will be the rate of tread wear and what will happen when it is time to recap the tires. Goodyear says that the sealing compound in DuraSeal tires will stay intact and that the casing will be treated the same as any other casing for tire retreads.
Pabst says that at the end of the day, he will look at the total lifecycle cost of tires with DuraSeal technology versus the total lifecycle costs of tires without the technology.
– Aaron Huff