How Technology Drives All-Weather Tires
By Curtis Brison, Vice President, Passenger and Light Truck Sales, Hankook Tire America
You may be surprised to learn that at any given time, only a few inches of your tires are actually in contact with the road. Understandably, this “contact patch” is considered one of the essential factors in determining how your car handles and performs. Since the first iteration of a radial tire at the turn of the 20th century, tire technology has advanced significantly to allow for better performance in a variety of driving environments. And because weather can be unpredictable with fluctuating temperatures and a seemingly revolving door of climates, this same technology has given rise to all-weather tires, which as the name suggests, are driven to perform no matter what Mother Nature throws at you.
Two of the primary performance indicators of a tire are the composition of its compound (rubber) and tread pattern (grooves), which help the contact patch adhere better to the road in different driving conditions. An all-weather compound boasts a more flexible operating temperature and a better glass transition point (more on that in a moment) than the traditional all-season tire. With both summer and winter tread elements, all-weather tires, like the Hankook Kinergy 4S2, are a new hybrid segment you’ve likely never heard of until now.
The Science Behind Hybrid Compound and Tread Technology
Driving on winter tires in the summer or summer tires in the snow brings considerable hazard for the tire’s durability, performance and your overall safety. Take for example, a summer tire’s compound. The compound is soft and pliable in warmer temperatures to give you better grip for acceleration, stopping distance and cornering ability, while providing the best possible performance for your car in that environment. If driven in colder temps (sub 40˚F), the tire would become hard, brittle and much more challenging to drive. And that’s without even discussing the role of tread patterns in all this.
In scientific terms, this is what’s known as Glass Transition Temperature – and something unique to polymers, including the rubber used in your tires. Consider what happens when you leave a plastic painter’s bucket outside during the winter. It cracks or breaks more easily than when left outside in warmer seasons.
Determining that Glass Transition point or temperature range requires a specific ratio of involved materials to achieve the ideal blend for the intended environment and use. In this case, having a broader operating temp for an all-weather tire allows for a pliable tire in the winter while not becoming overly rigid and sacrificing durability and performance in warmer weather.
We’ve established that the two largest influences around a tire’s design and performance function are compound and tread pattern. An all-weather tire has an operating temperature that is significantly broader than a conventional all-season. On a material science level, a highly refined resin derived from pine leaves and other natural ingredients is adopted to improve wet and snow performance, serving as the foundation for a tire’s compound.
Complementing an all-weather’s dynamic compound, the tread incorporates key elements and patterns from both sides of the summer and winter spectrum. Compared to an all-season that incorporates mostly vertical and parallel tread sections, a winter tire and by hybrid association, an all-weather tire, features horizontal sections or a zig-zag pattern to provide additional digging force and a biting edge for ice and snow traction.
With the inclusion of sipes or small grooves at the top of the tread block, this tiny but important feature helps improve stopping distance and overall traction by packing in snow to those etches. Yes, you read that right. Despite popular belief, snow is actually very sticky onto itself and packing snow to the right areas of your tire’s sipes helps facilitate additional traction, not unlike making a snowball with your hands or rolling snow on the ground to make a snowman.
Assisting with slightly warmer conditions and wet surfaces, an all-weather tire will include a second set of sipes that function in a similar fashion but designed with Summer performance in mind by having straighter etches to help with breakaway traction and stopping distance. Also located near the outside or shoulder of an all-weather tire, you’ll notice wide lateral grooves that allow for proper water evacuation and dispersion when driving over road elements such as puddles rather than hydroplaning across.
Where All-Weather Feels Right at Home
All-weather tires are a sure-fire way to make sure your bases are covered across all seasons. While they don’t share the same dedicated performance of a winter tire, all-weather tires with the three-peak snowflake rating on their sidewalls have passed specific inter performance parameters set by the Department of Transportation. Another added benefit for most is not having to change tires between season –reinforcing the all-weather segment as offering “the right tool for the right job.” Tire technology and innovation provide us with those tools that can not only make your car perform better, but increase the overall safety and efficacy of your daily commute or weekend getaway.
So which tire is right for you? All in all, it ultimately comes down to knowing your surroundings and your driving environment. If you experience a mild winter with doses of light snow, slush and cold weather (not arctic tundra), but need more tread and compound power than an all-season, that’s where an all-weather tire shines.