Modern passenger car tyres have a complex structure. The rubber tyres we drive on today have been in the making for over a century. We have played a major role in the development of today’s steel-belted radial tyres, improving tyre design and function. Read on to discover how as we dissect the modern tyre.
Tyre components can be grouped into two main structural elements: The tread and belt assembly and the casing. These elements consist of several layers.
Starting at the road surface and working our way to the core of the tyre, let’s take a look at the individual components. We’ll also discover what role these components play.
Let’s start with the outer layers that make up the tread and belt of the tyre. This principally rubber component envelops the casing and provides low rolling resistance, optimum handling, a long life and good petrol mileage.
1. Tread. Made of synthetic and natural rubber. On a new tyre, this textured surface ensures high mileage, good grip on the road and water expulsion. This equates to safe driving in all conditions. Tyre tread connects with the road and the sidewall, and has three areas:
Continental’s contribution. In 1904, Continental was the first tyre manufacturer to introduce a tread pattern to the pneumatic tyres of the time.
2. Jointless cap plies. This layer, which sits directly below the tread, enables travel at high speeds. Imagine gathering a length of twine back into a ball, coiling it around and around. Jointless cap plies are a little like this. They consist of a single, strong cord of nylon, embedded in rubber. This cord spirals around the circumference of the tyre, from one side to the other, without overlapping.
Our contribution. A woven linen fabric embedded in rubber used to perform this function. But the crossed threads would rub against each other, resulting in a shorter tyre life. In 1923, we introduced a new cord fabric. This fabric (described above) featured cords running in one direction held in place by supporting threads, embedded in rubber. Tyres incorporating the new fabric lasted much longer.
3. Steel cord belt plies. Strong steel cords provide the tyre with rigidity in this layer, which:
Now let’s discover the interior of the tyre, known as the casing or carcass. The casing cushions the tyre and contains air – functioning like an inner tube. It’s the air – not the tyre itself – that carries the load. That's why inflation pressure is so important. Anyone who has ever had a flat tyre knows this well!
4. Textile cord ply. This layer of textile – namely rubberised rayon or polyester – controls the internal pressure of the tyre and maintains its shape.
5. Inner liner. An airtight layer of butyl rubber that fulfils a couple of crucial functions:
6. Sidewall. The exterior wall of your tyre – connected to the tread by the tread shoulder. Made of natural rubber, the sidewall protects the casing from external damage and atmospheric conditions.
Part of the casing, the tyre bead component makes up the edge of the tyre that sits securely on the wheel groove. It’s here that the tyre is held in place on the wheel thanks to air pressure. The bead is made up of three parts.
7. Bead reinforcement. Made of nylon or aramid – a type of strong, heat-resistant, synthetic fibre, this fine cabling:
8. Bead apex. A stabilising wedge of synthetic rubber. The bead apex performs the same tasks as the bead reinforcement while also providing additional steering comfort.
9. Bead core. The heart of the bead, made up of steel wire embedded in rubber. The core ensures that the tyre sits firmly on the wheel rim.
Read more here about how these components come together in the tyre-building process.