Life, as the saying goes, flies by. A few months ago, my wife was driving home from work in our beloved 2007 Ford Explorer when a driver driving in the opposite direction fell asleep at the wheel and drove into oncoming traffic right in front of her. While she was fortunate to be uninjured, our sturdy SUV was not so lucky.
You suddenly found yourself in need of replacement tires during a particularly turbulent time in the used-car market. You figured you’d stick with tried-and-true tires and found a 2008 Explorer that fit the bill. But before you could even put your latest purchase to the test, you took it to your mechanic, who pointed out that your eight-year-old all-season tires were well past their use-by date, even though they still had plenty of tread left.
Noting that this Explorer is equipped with a proper four-wheel drive system, I decided to check out what options there were for factory-sized all-terrain tires, which led me to the Cooper Discoverer Road+Trail AT. A successor to the popular Discoverer AT3 4S, the Road+Trail AT is designed to handle rough surfaces without compromising on-road performance. While I envisioned winter trips to the mountains and exploring off-road parks, the reality is that, like most all-terrain vehicles, this SUV will spend the majority of its time on paved roads.
Until recently, choosing chunky all-terrain tires came with the drawbacks of increased road noise, unstable steering, and impaired handling in everyday use. However, after testing vehicles like the Ram 1500 TRX and Ringbrothers 1970 Chevy K5 Blazer, we were pleased to find that tire manufacturers have made great strides in these areas in recent years, and the Cooper Discoverer Road+Trail AT doesn’t buck the trend. In fact, after the new tires were installed, the Explorer’s on-road handling improved, and we didn’t notice any increased road noise compared to the much docile all-season tires it was replacing.
So I wondered what’s driving advancements in tire design and reached out to Cooper Tire, who introduced me to Jenny Page. Currently director of North American product marketing for Cooper’s parent company Goodyear, Page oversaw the development of the Discoverer Road+Trail AT in her previous job and graciously agreed to talk about this project. She said a variety of factors have allowed manufacturers like Cooper to significantly improve tire design in recent years, with a few advancements that stand out:
“The computer modeling we use in the tire development process has come a long way, allowing us to create more subtle variations in tire design before we even build a physical prototype. For example, if you look at the tread pattern on our Discoverer Road+Trail, it appears to repeat around the circumference of the tire, but there are actually small variations in the size and shape of the tread lugs that make up the pattern. One big reason we do this is because airflow has a big effect on the road noise a tire produces, especially with all-terrain tires. By using computer modeling to optimize the shape and size of the tread lugs, we can churn up the air passing by the lugs, breaking up turbulence and preventing increased sound waves.”
She also explained that one of the challenges of developing an all-terrain tire like the Discoverer Road+Trail is that it needs to perform well across a wide range of criteria, some of which are polar opposites of each other.
“There’s an incredible amount of chemistry that goes into a tire’s tread compound. It’s not just the raw materials that you mix together to make the rubber that makes up the tread, but the way you mix them together. This isn’t something that consumers see, it’s a kind of ‘secret sauce’ in tire design. For example, this tire has the Three Peak Mountain Snowflake symbol, which means it meets the American Tire Manufacturers Association’s requirements for harsh winter conditions. To get traction in those conditions, the tire compound needs to be soft, and the compound needs to be able to stay supple as the temperatures drop. Typical all-season compounds tend to harden when it gets cold, which makes them very slippery on the road. But because this is an all-terrain tire, the compound needs to be tough and able to withstand uneven terrain, rocks and other obstacles. So the trick for our engineers is to find the ‘sweet spot’ of a compound that can perform well in both situations.”
While the compound also affects how the tire will behave under normal weather conditions, Page said the sidewall design plays a big role in a vehicle’s ability to keep straight on the road. But while a stiffer sidewall can reduce steering disturbances, it can also negatively impact ride comfort, so engineers are faced with a balancing act here, too.
“Keep in mind that there are many different types of rubber inside the tire, especially down the sidewall, where it meets the wheel. There are some very hard compounds there that help with tracking and responsiveness. But we also need to look at ride comfort as we search for that sweet spot. There’s no one tire that can do it all without compromising, so it’s important that we really understand our potential customers’ priorities for the tire we’re developing.”
While computer modeling has become a key element of tire development, real-world testing remains a vital part of the development process: Once Cooper has narrowed down a design, prototypes are built and evaluated at the company’s test track in San Angelo, Texas, and other facilities that can replicate extreme conditions.
The data collected allows prototype tire designs to be sent back to modeling labs for further tweaking or for additional lab testing with proprietary equipment that measures properties like abrasion resistance and tensile strength. Though improvements are often subtle, the end result of this process is a higher-performing, more durable and ultimately safer tire.
