The Relationship Between Tire Traction and Tread Design

The Relationship Between Tire Traction and Tread Design

Understanding the nuanced differences between different tread designs can be valuable for communicating the value of different tire options.

Virtually every element of the tire tread, from the number and size of lateral grooves to the overall void area to the radius of the contact patch, can be optimized for specific driving conditions. Understanding the relationship between tread design and tire traction, especially for specialized driving conditions, can be valuable when educating customers on the differences between all-season and winter tires.

Smithers-Dry-traction-1400

Optimizing tread design for dry driving conditions

Dry traction generally refers to traction on an asphalt or concrete surface under ideal conditions, with no risk of slippage due to water, snow, or ice. A tire optimized for dry traction will be designed to maintain contact with the road surface when the tire rotates. There are a few specific engineering and design strategies that can facilitate this:

  • The contact area of the tread is increased, while void areas, such as grooves, slots, and sipes, are decreased.
  • The tie bar is maximized to minimize squirm in the footprint area.
  • The depth of the tread is decreased.
  • The tread compound is optimized for dry traction based on the physical design of the tread compound. 

Racecar tires provide an excellent example of a tire tread that has been optimized for dry traction to an extreme degree. Race tire treads have very high contact areas, with very few voids, and premier raw material technology for maximum performance for wet and dry traction. The technology utilized in race car tires is eventually transferred to passenger car and light truck tires.

Smithers-Wet-traction-1400

Optimizing tread design for wet driving conditions

Wet traction refers to traction on a wet road surface, usually asphalt or concrete. The performance of any given tire under wet traction conditions can differ significantly depending on the depth of the water, the speed of the vehicle, and other variables. An extreme example of wet traction loss is hydroplaning, a phenomenon in which a tire completely loses friction and contact with the road surface.

A tire optimized for wet traction will be designed to evacuate water from the footprint area as quickly as possible so the tread can maintain contact with the road surface:

  • The depth of the tread is increased.
  • The size and quantity of void areas are maximized. Circumferential grooves are made larger, as are lateral grooves in the shoulder and intermediate ribs. All ribs have more, larger sipes.
  • Tie bars are minimized to avoid constraining the slots and shoulder grooves and inhibiting water evacuation.
  • The tread compound is optimized or developed for wet traction performance.

It’s worth noting that wet traction optimization strategies in terms of tire pattern design are contrary to those employed when striving to optimize for dry traction.

Smithers-Snow-traction-1400

Optimizing tread design for snow driving conditions

Snow traction refers to traction on snow-covered surfaces. There are countless variables that can affect snow traction performance, including snow depth, compaction, and structure, such as fresh flakes versus hardened crystals. Snow conditions can vary dramatically throughout a given winter season or even a given day.

While dry and wet traction are determined by the ratio of surface area to void area, snow traction relies on the abundance and density of biting edges in the tread that can grab the snow. There are several strategies to consider for maximizing biting edges:

  • The contact area is decreased, the void area is increased, and tread depth is maximized.
  • All lateral structures are maximized. For example, sipe quantity and size is increased in all five ribs of the tire.
  • Tie bars are minimized to reduce the constraint of elements and allow for squirm and more deformations that produce biting edges.
  • The tread compound is designed for improvements in snow and ice traction. Specifically, the tread compound is formulated for lower durometer and lower static/dynamic modulus to allow for greater flexibility throughout the tread in cold temperatures.

What about all-weather or all-season tires?

Some people faithfully switch to winter tires every year when the snow starts to fall. But in climates that only experience mild or occasional snowfall in winter, this may not be necessary. And of course, switching to a designed wet traction tire every time it rained would be incredibly impractical, even if such a specialized tire existed. The most sensible, convenient, and cost-effective option for most drivers is to drive on all-weather or all-season tires year-round.

All-weather or all-season tires are designed to perform reliably in a wide range of conditions. However, the tread design strategies for optimizing tire traction performance for one set of conditions are often the exact opposite of the strategies for another set of conditions. This requires tire engineers to make design decisions in order to develop a tire tread that performs well in a variety of driving conditions, even those demanding different strategies for traction performance optimization.

Testing during the research and development stage is critical for designing all-weather or all-season tire treads. Tire engineers can objectively assess the performance of different tire tread designs in a controlled environment to determine which design is best for year-round use. Testing methods include compound development and machine-mounted testing in a laboratory as well as on-vehicle testing on a designed track.

Why this matters for independent tire dealers

Understanding the nuanced differences between different tread designs can be valuable for communicating the value of different tire options with customers. This is especially true when discussing snow tires. As previously mentioned, all-season and all-weather tires are appropriate for many drivers, but in some climates, winter tires can be the more appropriate choice. If a customer is hesitant to spend money on specialized tires or wants to learn more about how winter tires differ from all-season or all-weather tires, dealers can explain the unique characteristics of winter tire tread design and how it translates to better traction on snow-covered roads. As a result, the customer has a greater understanding of the tire’s value and greater confidence in the dealer’s expertise, which may result in more sales.

Josh Guilliams is the vice president of consultancy at Smithers.

You May Also Like

Editor’s Notebook: People Make Perfect in the Tire Industry

In the tire industry, it’s all about the people. Why? Because in today’s world, that’s just good business.

Editnotes-oct-1400

The time has come again for my favorite edition of Tire Review: our Top Shop issue, now in its 17th year!

Tire Review’s Top Shop Awards Program, presented by Coats, recognizes the “best of the best” tire dealers across North America. A common theme among many of our Top Shop winners over the years is the idea of treating their employees and customers like family. It’s one thing to say it – everybody says it. It’s another thing to truly live and breathe that mentality.

The Benefits of Continuous Learning in the Tire Industry

The first step in any successful training program is to identify what’s important for your staff to learn.

training-shop
Mass. Lawmakers Could End Right to Repair Impasse

A Boston Globe editorial suggests that the state legislature “might be able to break the stalemate.”

Mass-lawmakers right to repair
AI & Your Tire Shop: Using it to Your Advantage

AI could revolutionize the tire industry. It’s time to adapt and invest for success.

AI Stock image
Finding TPMS Sales & Maintenance Opportunities

Follow five steps to keep TPMS systems functioning properly.

Low-PSI-TPMS

Other Posts

Important tips for wheel bearing service

Complaints like exhaust leaks to tire balance issues to vague statements like “it just doesn’t sound right” may mean bad wheel bearings.

TR-Continental-Important-tips-for-wheel-bearing-service
Sonic Tools USA offers tools to beat back the technician shortage

Andrew Coccari, VP of Sales and Marketing at Sonic Tools USA, delves into the causes of the technician shortage and offers some novel solutions to address the need for help around the country.

WT YT-Sonic-Tools-1400
Sally Thomas taps into her tenacity to build on the success of her family’s tire business

Today, Sally Thomas and her brother, Bryan, operate eight retail stores, two commercial locations, three wholesale distribution warehouses, a Mighty Auto Parts franchise, and an e-commerce business.

sally-thomas-1400-REV
Three facts about modern electric power steering

EPS has enabled key vehicle advancements like stop/start systems, hybrids and advanced driver assistance features or ADAS.