They’re ’round and black’ is how most people see car tyres but they’re not all the same. We explain everything you need to know about car tyre tread pattern.
When it comes to car tyres there is a hell of a lot going on. Indeed, do you know your Symmetric from your Asymmetric, or Directional tread pattern? Read on.
Tread Pattern Explained
There are three main types of tread pattern and these are Symmetric, Asymmetric, and Directional.
Imagine a line through the centre of the tyre. Symmetric tyres look exactly the same on each side. They are the most common tread type and they’re often referred to as multi-directional, meaning they work just as well in reverse as forwards. This also means the tyre can be changed from side to side and it will always be rotating in the direction it is designed for. Read more about tyre rotation HERE.
When to choose symmetric tyres: Symmetric tyres are the cheapest, and easiest to live with as they will work on any corner of the car, backwards or forwards. They tend to be the cheapest to buy. They are also the best choice for offroading as that’s one area where you often need as much traction going backwards as forwards.
An asymmetric tyre has a different tread design on the outer half than the inner half. The inner half is optimised for use in wet conditions, and the outer for dry use. Despite the fact they are asymmetrical, you can still rotate a tyre from left to right, so your tyre rotation strategies still apply. Directional tyres have a marking on them incidating which edge is the outside edge.
When to choose asymmetric tyres: Asymmetric tyres offer improved wet and dry performance over symmetric tyres. These tyres are generally more expensive than a symmetric tyre as they’re more sophisticated in their design and construction.
These tyres are designed to rotate in only one direction, and they always have an arrow on the sidewall indicating the direction the tyres should rotate. Look at the face of the tyre and you’ll see the tread is generally V-shaped.
When to choose directional tyres: When you want the best possible performance in a forwards direction. This is why racing tyres, and often sports car tyres are directional. Because the tyre designers don’t need to worry about the tyre working in reverse, they can optimise the design of the tyre for one direction only. However, you can’t then swap a tyre from left to right, unless you physically remove the tyre from the wheel and flip it around.
The four parts of a car tyre’s tread
There are four parts to a tyre tread:
- Tread blocks – raised chunks of the pattern that contact the road;
- Ribs – raised sections of the tread pattern that are composed of tread blocks;
- Slots – channels moulded into the tread to help drain water away from the surface of the tyre.
- Sipes – small rubber teeth on the shoulder of the tyre that provide additional bite when on dirt roads or in ruts. They are more pronounced on offroad-oriented tyres.
Other types of tread design
Construction: this is how the tyre is constructed, essentially how strongly it is made. A thick skin with metal interwoven in the tyre means a tough tyre that resists punctures and takes a load, and that’s “light truck” or LT construction. These are recommended for trucks and 4X4s that go offroad. But that construction is expensive, handles poorly and uses a lot of fuel. Roadcars run “P” construction which is a Passenger tyre design, much lighter and less heavy-duty, and the “XL” (eXtra Load) construction is part-way between the two.
Tread design: tyres may be designed for the racetrack, or for mud. The looser and softer the surface, the greater the depth of the tread block. Tyres used on 4x4s are a compromise between on-road and off-road performance, with all-terrains trying to perform well on both surfaces, whereas mud-terrain (which are not just for mud!) are more focused on offroad performance, but at a greater cost, noise, and poorer handling that all-terrains. Some sports car tyres designed for the track are not suitable for onroad use, or in cold conditions. It’s all about what a tyre designer prioritises – you can’t have it all.
Staggered tyres: this is where different sized tyres are run on the front to the rear to optimise performance, common on high-performance cars such as the Supra we’ve just tested.
Stay tuned for more guides and explanations on tyres and everything else you need to know about cars
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