Why do tyres have tread

Tyre treads are rubber components inside car wheels. They provide the needed traction for a vehicle to move forward, turn and even stop. They differ from the rubber in car tyres because they come with a solid pattern rather than round or square-like tyres. Three basic types of tread patterns are used during tyre design: wire-spoke, chevron, and alphabet letters.

Tyre treads are made of several layers of rubber with an outer skin that develops wear patterns due to friction between the tread and the road surface. Such wear and tear will eventually cause a flat spot on the tyre's tread surface.

This can lead to premature tyre wear and tyre-roadway contact, which can lead to the failure of other vehicle parts, such as the suspension system, steering gear, springs, shock absorbers, and engine mounts. There are a lot more reasons tyres have treads. Read on to learn more about why tyre treads are essential.

Benefits of Tyre Treads

Resistance against hydroplaning

Hydroplaning is a major concern for drivers during wet-weather conditions. This happens when a vehicle's tyre is not in contact with the road surface and instead resides on a thin layer of water.

It can lead to poor traction and loss of control, which may result in an accident. Treads improve traction as they "dig" into the road surface and provide resistance against hydroplaning.

Improved braking performance

When your car has less tread depth, it may have insufficient friction between its tyres and the road surface, which could cause skidding (understeering) when braking on a dry road surface.

This is because the tyres have insufficient grip to push the car forward; hence they have to slow it down (understeer) instead. By contrast, having deeper treads ensures that your tyres can maintain contact with the road surface and reduce stopping distances.

Burnishing of the tread blocks

Tread blocks on tyres can become flat when they encounter a strike or bump in the road. This is why regular driving on a flat tyre can result in a permanent loss of air pressure and require immediate replacement.

However, when tyre treads are deep and have more significant surface area contact on the road, there is a lesser chance for flat spots to develop. Smaller objects on the road would be less likely to impact and damage the tyre's surface.

Improved wet-weather traction

Tread patterns are designed to channel water in a specific direction away from the car's stopping and braking mechanisms. This prevents hydroplaning and increases grip during wet weather driving conditions.

This also applies to how water interacts with a car's tyres while turning on a rainy day, allowing it to flow around the vehicle much more efficiently instead of being dragged across, reducing resistance.

Reduction in rolling resistance

Rolling resistance is a property of any tyre. This means that its resistance to movement (in other words, friction) depends on its size (carcass surface area) and tread depth. When an object, such as a tyre, constantly moves against another object, like the ground or another entity (for example, a bicycle wheel), friction applies between both objects over time.

Wear resistance of the tyre

Wear resistance occurs when a material is compressed repeatedly to its elastic limit until the load is removed. It returns to its original dimensions while it retains some residual deformation.

This occurs when a vehicle drives over rough surfaces or potholes at high speeds, which may lead to premature wear and deterioration of the tyre's treads and possible damage to other car parts such as the suspension system, springs, shock absorbers, steering gear, and even engine mounts.

However, deep treads provide additional surface area for the tyres to come in contact with on the road surface during such driving conditions; hence they are less likely to experience wear.

Reduced noise

Tyres with low tread depth produce more noise as they make direct contact with the road surface when rolling. This is because the rubber tyre sidewalls are compressed, which in turn causes the tyre to "scrape" across the road.

However, low tread patterns provide a larger surface area for the tyres to come in direct contact with on the road surface during such driving conditions. This helps reduce vibrations and a "scraping" noise that car passengers may experience.

Greater level of damping

The level of damping is a characteristic of any vehicle's suspension system, which measures how much resistance a chassis has against unwanted motions or vibrations. A car's damping depends on the rubber in a tyre's sidewalls, which gives the chassis the ability to return to its original state after being subjected to harsh driving conditions.

This allows for sufficient tyre-roadway contact, which ultimately results in optimal handling.

Improved fuel efficiency

A vehicle's tyres comprise a significant portion of its total mass, carrying the car's weight. The greater the circumference of a tyre's footprint (1/3 larger than its diameter), the more efficiently it converts fuel energy into potential mechanical energy during rotation.

This is because it takes less energy to move larger masses. In addition, having deeper treads allows for smoother rolling of tyres, which produces fewer vibrations and thus results in greater stability when travelling at high speeds.

Factors to Consider When Replacing Tyre Treads

Tread depths

The tread depth of a tyre is measured from the centre line of its tread centre to the edge of the outermost (major) rib. This will determine how much grip a tyre has when driving on a wet road surface.

Tyre treads may become discoloured after repeated exposure to severe driving conditions (e.g., heavy rain, black ice, potholes, snow, etc.). In addition, excessive wear and poor shape of an existing tread pattern can lead to reduced traction in wet weather conditions.

Wear pattern

If tyres have irregular wear patterns, they may not provide good traction when going over rough roads. This can cause "bottoming out" on specific surfaces and affect stability and safety during extreme driving conditions. Repetitive wear and tear can also lead to excessive tyre tread depth, primarily affecting a vehicle's braking ability.

Vehicle weight

Vehicles are designed to have their specific tyre pressure and load capacity. For example, a vehicle's weight may cause the inner portion of a tyre's tread to become flattened at the centre, consequently reducing its ability to maintain contact with the road surface, thereby reducing stopping distance. If this is not addressed, total tyre life will gradually decrease due to a lack of support from an area directly under the tread.

Tyre width

Tyres wider than 1.6 inches (40 mm) can take longer than usual to rotate when driving over uneven roads, especially at high speeds or when braking. This can affect vehicle handling when cornering. In addition, the greater the width of a tyre, the longer it will take to react to steering inputs.

Driving conditions

Driving conditions such as frequent driving on wet roads (or even sandy ones) may cause a tyre's tread profile to become heavily worn and unbalanced. An uneven profile on each tread block can also cause reduced stopping distances due to improper contact with the road surface during braking and increased fuel consumption due to excessive tyre rolling resistance.

The result will be reduced traction in wet weather conditions, which may increase tyre noise levels while cornering or driving over uneven surfaces at high speeds.

Categories of Tread Patterns

Symmetrical

This is the most common type of tread pattern on passenger and sports cars. Its centre is usually the same width from side to side but may vary in thickness from top to bottom. Its advantage is that it is simple to manufacture, provides good traction on different surfaces, and can be manufactured relatively quickly.

Asymmetrical

This tread design is more popular for off-road vehicles such as 4x4s and all-terrain vehicles (ATVs), which often require varying sizes of tyres for different terrain types (e.g., sand, mud).

This tread design is also used in some non-passenger vehicles, such as off-road SUVs and trucks, farm machinery, race cars, and motorcycles. It is an irregularly-shaped tread pattern with a deeper tread in the centre and a thicker tread on the outside edges.

Modified asymmetrical

A modified asymmetrical is similar to the asymmetrical, except that it has a flatter centre than its outer edges, reducing rolling resistance but providing little additional lateral grip. This can be beneficial when travelling at high speeds in off-road conditions where traction is critical due to loose terrain and poor road surface conditions.

Such a tyre pattern can exhibit an advantage over conventional asymmetrical tyres when driving on dry roads due to reduced noise and improved handling.

Offset

The offset tread can be described as the reverse of symmetrical, where the centre tread is thinner than its sides. This design reduces rolling resistance and allows for better directional control in a straight line on dry and wet roads.

The diffuser area creates half of the tyre's tread pattern, providing a larger contact patch with the road, which increases traction. It is also beneficial in off-road conditions due to increased traction.

Directional

This tread design has no central channel and a pattern of varying widths. This allows for better traction on ice, snow, and loose surfaces like sand. A directional tyre may also have multiple small grooves for suspension, which improve steering feedback during cornering.

Having High-Quality Tyre Treads is Important

The driver must ensure the vehicle's safety while improving the overall driving experience and reducing fuel consumption. It is also essential to do all you can to keep the costs of driving down, and nothing can be more costly than tyre wear.

When choosing a tyre tread, one of the best things any driver can do is to ensure that you are purchasing the right kind for the road conditions and your driving style. Similarly, when buying a new or used car from a dealership, tyre treads are essential to consider before making a purchase.