Gripping Asphalt: What Treads Do to Keep You on the Road

Tire treadMost people know how a tire should work; it allows the wheel to get a better “grip” on the road. But there are only a surprising few who understand what engineers mean when they say grip. First, the feature that allows the tire to grip the road are the tire treads, and it does so by utilizing two forces – traction and friction.

Tire experts from All Star Tire share that this is where many people start to get lost because traction often gets confused with friction as the same thing. The two concepts are actually very close, but they have as much in common as an orange tree does with its seeds; confusing the two would be a mistake.

Friction Isn’t Traction

Friction hardly needs an explanation; it’s the force that resists the relative motion of solid surfaces. Traction, on the other hand, is a process wherein the tangential force is transmitted through two objects via friction. Using the orange tree analogy one more time, friction is the seed and its growth into a tree is traction.

The tire needs to have as much contact with the road as possible in order for it to perform. This is what engineers mean when they say grip, maximizing surface area contact, increasing friction, and utilizing as much traction as possible. But rubber is a horrible material to do this with, since it has a very low coefficient of friction. Fortunately, the answer is simple – treads.

The Real Job of Treads

People often imagine treads acting similar to fingers when engineers talk about grip, but that’s not how they work. This line of thinking assumes that the treads alone are responsible for maintaining grip, when in truth it’s the entire tire that’s responsible. The design of treads is to allow water and whatever debris on the road, such as mud and snow, to escape from underneath the tire. This minimizes the material’s interference with the traction.

When a car runs over a slick road, the vehicle is essentially driving over water, depleting both friction and traction. Eliminating as much of that variable as possible allows the car to maintain enough friction and traction to be able to meet its expectations on performance.