Introduction to Tread Pattern
Every tyre comes with a different pattern design engraved on it. The common misconception here is that each pattern signifies the extent of grip the tyre might provide in any given condition. The pattern depth though is an important indication of the tyre’s traction ability while the pattern itself serves a different purpose altogether. Let’s look into detail at the importance of these design patterns and their classifications.
Better known as tread pattern, the design incorporates specific design features for optimum performance in different conditions. The design is carved out on rubber into ribs, channels, sipes, grooves, and independent tread blocks. The variations in these define the design pattern of the tyres. These designs help the tyres in providing grip, traction, rolling resistance, and aquaplaning resistance. These also have an effect on road noise, wear rate, handling and braking depending on the driver and driving conditions.
Types of Tread Pattern
Symmetric Tread Patterns:
The most commonly used tread pattern is the symmetrical pattern. As the name implies, it has identical halves patterned with continuous ribs, independent blocks and more commonly a wavy design pattern, across the entire tread face. They are extensively used in small city cars, are comparatively affordable and involve less effort in fitting. It also has a greater straight-line ability owing to the singular tread pattern, and are convenient for ‘tyre rotation’ (which you’ll read in detail in upcoming articles). On the downside, symmetrical tyres are not suitable for all-round use such as off-roading, wet or snow; while excessive cornering would cause uneven wear resulting in lower traction in rain and reduced tyre life.
Asymmetric Tread Patterns:
An asymmetric tread design is characterised by different halves of the inner and outer tread pattern. Asymmetric tread patterns combine the features of other tread designs for equally strong, dry and wet performance. The outer side of the asymmetrical pattern has a larger tread block which is designed to provide larger traction and stiffer ride for enhanced handling and cornering stability. It also helps to reduce tread squirm and heat build-up on the outside shoulder. Whereas the inner side has open shoulders and a number of grooves to disperse water and limit the risk of aquaplaning. Such types of tyres are specifically designed for mid to high-end cars in order to improve safety on both wet and dry roads.
However, these tyres are expensive compared to symmetrical tyres. Apart from that, special care must be taken while installing these tyres. And hence asymmetric tyres have words like ‘Outside/Inside’ stamped on the sidewall to ensure they are fitted with the tread block facing the correct way.
So this is how the tread pattern is classified depending on their design. However, while at it, it’s important to consider the directional tread tyres as well. These tread patterns are of two types – unidirectional (or simply directional) and multidirectional.
A directional (unidirectional) tyre, as the name implies, can be rolled only in one direction. They usually have a tread design pointing forward in the same direction, meeting at the centre line of the tyre, thus making a V-shaped pattern. Such tyres are very efficient on wet surfaces with enhanced hydroplaning resistance at high speeds by pumping water more efficiently through the tread pattern. They also perform well on snow covered roads and hence many winter tyres have directional tread patterns. On the directional tyre patterns, you’ll notice arrows on the sidewalls pointing in the direction that tire needs to be mounted. Rotation wise, these tyres can only be rotated from the front axle to the rear axle on the same side, otherwise, the tread pattern will rotate in the wrong direction when mounted on a wheel on the other side of the car.