As you can imagine, it is easy to take your tyres for granted and whilst we try to encourage vehicle owners and drivers to check their tyres and tyre treads or get help from our extensive network, few people actually appreciate what they made from.

Surprisingly there are over 100 components in the average tyre ranging from textiles to steel cables and a variety of rubbers and chemical compounds depending on what property is required for that part of the tyre.

As part of the induction training at Tyrenet a number of our team have attended courses and factory visits to learn more about tyre production and the properties of tyres and all of them have returned to the office amazed at what they had learned and so they suggested we share some of that knowledge and our thanks to the contributors of this information.

Most people would know that tyres are primarily made of, rubber, which is combined with other different raw materials. Typically, tyre components include natural and synthetic rubber, carbon black, silica, numerous chemical ingredients, antioxidants, curing systems, and textile and texture reinforcement cables. All these components play a role in boosting the tyre’s strength, durability, and performance on the road. According to tyre manufacturer Michelin, there are over 200 ingredients on a tyre that play a critical role in their performance, safety, and efficiency.  While rubber is the primary material, it’s combined with other raw materials to make a complete tyre.

If you follow our monthly ‘Tyre Troubles Stories’  you’ll know from the failures we feature that tyres have different parts, including beads, bead fillers, the sidewall, belt plies, body ply, tyre casing, inner liner, and tread.  That’s a lot that can go wrong or wear out but also a lot of learning over the past 135 years since the first pneumatic tyre was invented by John Dunlop.

As you will have no doubt seen, technology and pushing the ‘envelope’ for speed and durability is very much the driving force on the Grand Prix circuit, with barely a lap being driven without a mention of tyres, compounds or the eager anticipation of a tyre change and pit stop.

19% of a tyre consists of natural rubber in passenger and light truck tyres, whilst truck tyres have a 34% natural rubber composition.

Natural rubber is sourced from a rubber tree as a milky liquid which is then mixed with acids to solidify it.

This material comes with certain performance characteristics for the tyres such as flexibility and helps prevent tears and cracks. As the main tread component, rubber is used because it can withstand different types of weather, maintain grip, and is less expensive than other options.

Synthetic rubber used in tyres is an output of the petroleum industry and produced from polymers of crude oil. In tyre manufacturing, there are two types of synthetic rubber polymers used- styrene-butadiene rubber and butadiene rubber.

Used in combination with natural rubber, these materials make up 24% of the entire tyre in passenger and light truck tires and less so at 11% in truck tyres.

These synthetic polymers have different physical and chemical properties that determine the overall tyre performance and factors such as wear, traction, and rolling resistance.

Synthetic rubber used on tyres also has an important component, halobutyl rubber, which is essential because it keeps the inner liner impermeable and also keeps the tire inflated. 

Originally, tyres used to be grey-white before manufacturers switched to black. While there are still whitewall tires, tyre manufacturers started making black tyres by adding carbon black.

Carbon black is a soft, fine powder produced when natural gas or crude oil is burned using a limited amount of oxygen, creating a large amount of soot.

Together with silica, these two ‘fillers’ are critical in the tyre-making process because they reinforce the rubber as well as colouring it. Due to their properties, they improve tensile strength, tear, and abrasion.

Silica helps in boosting rolling resistance, and combined with carbon black, goes to ensure that tyres are durable.

On average, old passenger car tyres have steel that makes up about 10% – 20% of their weight; therefore, a shredding plant can produce about 100-200 MT of steel tyre wire during recycling. If you have ever seen a vehicle that has been burnt out or a tyre that was thrown onto a bonfire you will have seen the skeleton of the tyre as just a collection of steel wire hoops.

Manufacturers add these steel materials to help with puncture control, which improves the car’s safety. Steel wire is used in belt plies to help boost the tyre’s stability and strength too.

Steel is also added on the beads and the belts under the tread to improve handling and performance. Most tires have steel on the bead area, which is part of the tyre that comes into contact with the rim maintaining the strength of the connection to the wheel itself. 

In much the same way as glass reinforced plastic giving it a shape and different property or steel reinforces concrete giving it some flexibility, textiles which are types of fabric cords reinforce the tyre. These cords help to support the vehicle’s weight and provide dimensional stability.

In a tyre, the most common cords used are polyester cord, nylon, rayon, and aramid, which are used to make tyre plies in passenger tyres.

Textures are crucial in tyres because they act as the primary reinforcing material for your tyre casing, helping keep the tyre in shape. Because of this fabric, your tyres have the endurance to handle different road conditions.

 

Tyres are also made up of different chemical components that are antioxidants. These chemicals protect the rubber from breaking down after exposure to extreme temperatures and oxygen.

Where Does The Rubber In Tyres Come From?

Tyres are primarily made up of rubber, about 40-60%. Most of this material covers the tread and the sidewall, but where does this rubber come from?

This tyre manufacturing industry is one of the biggest consumers of rubber. Natural rubber comes from the Hevea trees originally from Brazil.

Today, manufacturers use a mixture of natural and synthetic rubber. While natural rubber is still sourced from the trees, synthetic rubber is derived from crude oil, which helps extend the lifespan of a tyre and boosts heat resistance.

During the manufacturing process, tyres go through curing, which is used to give the tyre its final shape. Manufacturers use chemicals such as sulphur and zinc oxide to transform the rubber into a solid compound.

The tyres are also treated with other chemicals including the unusually named antiozonants. These chemical compounds are used to help protect the tyres from the effects of exposure to the ozone layer.  Ozone is an unstable and reactive gas in our atmosphere, often created by lightning passing through the air which splits Oxygen molecules creating Ozone O3 which tries to combine to almost anything it comes into contact with effectively oxidising it.

Rubber provides a number of qualities that make it ideal for tyres.

1.       It Helps Maintain Grip

Your car needs to move whether it’s hot, raining, or the road is covered with snow, and for your vehicle to move in these different conditions, it has to have the necessary grip or friction with the road surface.

Rubber material makes it easier to grip the road surface and stay stable on slippery roads. It can maintain traction even on rough terrain, and that’s why manufacturers use it as the primary material.

2.       It Can Handle Loads

Rubber tyres are the go-to because they can carry loads. As a viscoelastic material, manufacturers combine rubber with compressed air to allow it to carry heavy loads comfortably. 

3.       It softens the ride

The relatively soft material of the tyre provides a cushion effect between the vehicle and the road and is therefore less noisy on the road.

Tyre manufacturers use a combination of natural and synthetic rubber, which extends the lifespan of tyres. For instance, synthetic rubber is less costly and helps the tyre withstand heat effects for longer than any other material.

 

1.            This is the tyre in different parts known as tread layers. Tyres have natural rubber in which is the main component of the tread layers. Metallic and textile reinforcement cables: the "skeleton" of the tyre, forming the geometric shape and providing rigidity. 

2.            Silica - Used as a reinforcing agent to improve durability. 

3.            Carbon black - Used for the same purpose of silica.

4.            Styrene Butadiene Rubber – A synthetic rubber made from petroleum. Oil may be added during manufacture this improves later processing. It has good grip and is mainly used in car tyres.

5.            Polybutadiene Rubber – A synthetic rubber made from petroleum. It has high wear resistance and a very long flex life. It is typically used on the sidewalls of a tyre.

6.            Natural Rubber – Produced from the latex of rubber trees. The latex is coagulated using acid, then mechanically dried. The resulting crumbs are pressed into bales, usually of 33 1/2kg weight. Its properties are high strength and tear resistance. A long flex life and a good grip. It is used in truck tyre treads.

7.            Natural Rubber (Ribbed Smoked Sheet) – Produced from the latex of rubber trees/ It is coagulated, using acid then rolled into sheets. These are then dried and smoked for preservation and made into bales of around 111kg.

 
Our thanks to Michelin for providing the content for this article.