A tyre’s tread pattern often attracts a lot of attention — with its appearance being referred to in ways that almost allows the tyre to take on a character of its own! Yet, whether it’s described as “grippy”, “aggressive” or just plain “interesting”, the tread pattern is about far more than merely good looks or sporty appeal — with each pattern a key aspect of the tyre’s engineering and performance.
A pattern with a purpose
Keeping in mind that the only thing between you and the road is the tyre tread, the tread pattern is a vital part of the tyre’s make up! Everything the driver does to operate the car is transmitted to the road through the tread pattern including steering, braking, acceleration and cornering under all road conditions – wet or dry.
As with all other elements of a tyre’s construction, manufacturers are continually improving and perfecting tread patterns for different road and vehicle types, weather conditions and other factors. Importantly, the tread pattern affects the tyre’s traction, handling, performance in the wet, dry and snow as well as different road surfaces, with its design including a range of features such as hydroplaning resistance, noise qualities, ride comfort and resistance to abrasion.
With the exception of some special applications – such as tyres for some race cars, and road roller/compactors (which may be smooth or “slick” tyres), all tyres have some form of tread pattern. Tyre tread patterns are particularly noticeable when the tyre is new or there is little wear, although their importance continues for the life of the tyre.
4 Essential tread pattern components
Every tyre tread pattern (for passenger on-highway tyres) is made up of four essential components. When arranged and combined, these components make up a specific pattern that is fit for a certain application or type of vehicle. These include:
Ribs are the raised section of the pattern which run circumferentially around the tread face. The ribs can be either plain or made up of some form of individual blocks.
Grooves as their name suggests are “grooves” or channels in the tread pattern that also run around the tread’s circumference.
Tread blocks are the raised individual elements set in a particular format and order that are the point where the tyre actually makes contact with the road or other driving surface.
Sipes are the small slits moulded into the tread face to increase traction in wet (by dispersing water) and other all- weather conditions.
4 Main Tread Patterns and their Features
There are four main tread patterns for passenger tyre vehicles – Directional (sometimes referred to as Unidirectional), Symmetrical (sometimes also called Multi-directional), Asymmetrical and Directional/Asymmetrical. Here’s a quick summary of each of these:
As the most common tyre tread pattern on passenger vehicles, the outer and inner sides of Symmetrical patterned tyres are identical with the tread blocks arranged continuously around the tyre. Once mounted to the wheel, the tyre can operate in any direction. This makes tyres with this tread pattern very versatile, usually providing a quiet ride and offering good grip on the road.
Directional (or Unidirectional) patterns are organised to operate strictly in one direction only — and tyres with this pattern have to be carefully fitted in the direction of travel. Amongst other features, this “V’ (or arrow) shaped pattern is known for its ability to evacuate water efficiently, providing excellent hydroplaning resistance – and is a good fit for all-season and high-performance tyres.
In the Asymmetrical pattern, the inner and outer areas of the tread are different. Each of these areas is designed with different channels and tread blocks. This enables them to perform in a range of all-weather and road conditions with the inner sides providing water dispersion, minimising hydroplaning and proving good handling and grip in the wet, while the outer shoulders provide excellent grip in the dry. The Asymmetrical pattern also ensures minimal noise.
The fourth common tread pattern is the Directional/Asymmetrical tread pattern, which is a combination of the Directional and Asymmetrical. Its features include both the “V” shape of the Directional pattern for expelling water, while also providing the benefits of the Asymmetrical pattern such excellent grip on dry surfaces.
Tread Pattern Performance
While each tyre tread pattern is carefully designed and manufactured to cater for certain conditions or environments, how do the performance of these various tread pattern designs compare?
The diagram below shows a general indication of performance parameters. These are:
- Directional Performance – i.e. straight line – includes steering response, braking, traction (acceleration) and aquaplaning resistance.
- Lateral Performance – i.e. sideways loadings on the tyre – includes handling, cornering and aquaplaning resistance.
Important Note on Rotation and Fitment
As you will have probably noted, the tread pattern (such as in the case of Directional tyres as mentioned above) will sometimes determine how a tyre can be rotated and fitted. So, for safety and performance reasons it’s important in most cases to keep tyres of the same tyre pattern on a vehicle, particularly when it comes to the front and back pairs.
Preferred patterns in modern tyre design
In today’s world, global tyre manufacturers and their R&D teams largely focus their efforts on Asymmetric patterns due to the significant advantages these offer over other pattern types. Asymmetric patterns not only offer more flexibility in terms of the arrangement of the block shapes and sizes on the inside and outside of the pattern, but also allow the tyre to be rotated side to side on the vehicle to maximise wear and extend the life of the tyre.