The tread is the part of the tire that makes contact with the surface of the road. And if you take a look at different tires on the market, you'll notice a great deal of variety in their tread patterns.
Why are they so different? Because a tread pattern is a unique design that enhances a vehicle with grip and handling for specific driving conditions. Just like in a detective novel, you could identify a make of tire by the tracks it leaves on the road.
Every tire tread has four constituent parts:
Taken together, the ribs, grooves, tread blocks, and sipes can be arranged in a unique pattern to modulate the tire's performance in critical areas like noise, handling, traction, and wear.
And that in turn provides tire manufacturers with the ability to develop tread patterns to address specific driving needs like wet braking, dry handling, aquaplaning (hydroplaning) resistance, and traction on ice and snow.
How many tire tread patterns are there? Quite a few. But broadly speaking, we can distinguish between three categories of tire tread pattern. Which one does your car have?
The most common type of pattern is symmetrical; it's suitable for passenger car tires, but not for high-performance use. Tires with this design have continuous ribs or independent tread blocks across the entire face of the tread, and both halves of the tire feature the same pattern.
Tires with symmetrical patterns provide the owner of the vehicle with the most flexibility for tire rotation without affecting day-to-day performance. They're also quiet, long-lasting, and fuel efficient. However, they are less adaptable to changing conditions on the road. So even though symmetrical patterns deliver steady grip on a dry road, they won't be as effective in wet conditions as other tires.
A tire with a directional tread pattern is designed to roll forward in one direction only. It has lateral grooves that meet in the middle of the tire tread, resembling the shape of an arrowhead. Its purpose is more than sporty aesthetic, however. The V-shaped grooves are more capable of resisting aquaplaning (hydroplaning) at high speeds by displacing water more efficiently through the tread pattern.
Another benefit of directional tread is extra traction, which provides excellent handling on snow or mud. For this reason, a good all-season or winter tire is highly likely to have a directional tread pattern. The extra traction is also useful for performance tires on high-performance vehicles.
The point to remember about directional patterns, however, is that tire rotation becomes a bit more complicated. They can only be rotated vertically – for example, from the front of the car to the back – otherwise, the pattern will be oriented in the wrong direction when fitted to a wheel on the other side of the vehicle. That would render the benefits of the tire tread useless.
You can keep track of the correct orientation using the arrow indicator printed on the sidewall of the tire. It's in the same direction as the pattern, pointing in the required direction of travel.
A tire with an asymmetric pattern features two separate tread designs, one on the inner half and another on the outer half of the tire. It looks unusual, but both halves serve a distinct purpose.
The inner tire tread is responsible for water displacement and protection against aquaplaning (hydroplaning). The outer tire tread has rigid tread blocks for higher lateral stiffness, which provides high grip when cornering and driving on dry surfaces, and quieter interior noise. This combination of features makes asymmetrical tires especially popular for use on ultra-high-performance cars.
However, just like a directional tire pattern, care must be taken with tire rotation. Vertical rotation between front and back are the options here. Indicators on the sidewall will guide correct fitting.
When buying new tires, avoid mixing different types, sizes, or brands of tire on a single vehicle. For best results, source the identical make and model of tire to the ones you already have on your wheels, to maintain optimal performance characteristics.
Another thing to keep in mind when replacing tires; replacing a pair of tires is safer than replacing just a single tire. The newest tires should be fit on the rear axle, and partially worn tires to the front axle.
If this isn't possible, then drivers are advised to ensure that the replacement tire has the same tire tread pattern as the other tire on the same axle. Mixing the patterns will impair the handling characteristics of your car; it could even be dangerous.