What Goes Into a Tyre?

 

   What Goes Into a Tyre?

When we think about tyres, we mostly see them as black rubbery rings around wheels. But beneath this simple appearance lies a complex combination of various ingredients, each playing a crucial role in how the tyre performs, lasts, and handles stress. From the flexibility of natural rubber to the toughness provided by carbon black and bead wires, tyre construction is a fine-tuned science.

In this blog post, we’ll dive into the key ingredients used in manufacturing a finished tyre. We'll look at the percentage share each component holds and explain why it's there. By the end, you’ll appreciate the technology that goes into something as everyday as the tyre on your car, bike, or truck.

 

What Is a Tyre Made Of? Ingredient Overview

A typical finished tyre is a blend of several components. Here is an approximate breakdown of the ingredient percentages found in a passenger vehicle tyre (composition may vary slightly depending on the type of tyre and manufacturer):

Ingredient	Approximate Percentage (%)
Natural Rubber (NR)	35–40%
Synthetic Rubber (SBR & PBR)	25–30%
Carbon Black	20–25%
Steel/Bead Wire	10–15%
Other Chemicals/Additives	5–10%

Let’s break down each of these components and understand their importance in tyre construction.

 

1. Natural Rubber (NR) – Backbone of Tyre Flexibility (35–40%)

What It Is:

Natural rubber is derived from the latex of rubber trees. It’s a biodegradable, elastic material that forms the base of most rubber compounds.

Role in Tyres:

• Flexibility & Elasticity: Natural rubber has exceptional stretchability, making it ideal for absorbing shocks and vibrations.
• Tear Resistance: It offers superior tear strength, especially under high loads.
• Wet Grip: It helps improve grip on wet surfaces, crucial for safety.

Why It’s Used So Much:

Its natural properties make it irreplaceable in many tyre applications, particularly for truck and heavy-duty tyres where strength and durability are key.

 

2. Synthetic Rubber – Stability and Specific Traits (25–30%)

Two Main Types:

• Styrene-Butadiene Rubber (SBR)
• Polybutadiene Rubber (PBR)

Let’s understand both:

(A) SBR (Styrene-Butadiene Rubber)

• Percentage Share: 10–15%
• Purpose: SBR offers excellent abrasion resistance and aging stability.
• Key Roles:
• Enhances durability
• Maintains grip over long-term use
• Offers balance between cost and performance

(B) PBR (Polybutadiene Rubber)

• Percentage Share: 10–15%
• Purpose: Used primarily in the tread and sidewall for improved performance.
• Key Roles:
• Superior wear resistance
• Low rolling resistance (helps improve fuel efficiency)
• Better resilience and crack resistance

Combined Use:

Synthetic rubbers are blended with natural rubber to provide a custom mix of performance and longevity. They also offer better uniformity and can be tailored to specific environmental conditions (heat, cold, etc.).

 

3. Carbon Black – Strength and UV Protection (20–25%)

What It Is:

Carbon black is a fine black powder produced by the incomplete combustion of petroleum products. It is used extensively as a reinforcing filler in rubber products.

Role in Tyres:

• Reinforcement: Enhances strength and durability.
• UV Protection: Shields the rubber from UV damage.
• Improved Wear Resistance: Reduces tyre wear, especially in high-friction conditions.
• Color: Gives the tyre its black color.

Percentage Breakdown:

Depending on the tyre's type (passenger vs truck), carbon black content varies. In high-performance tyres, it could be even higher for better heat dissipation.

 

4. Bead Wire – The Steel Backbone (10–15%)

What It Is:

Bead wire is high-tensile steel wire that forms a ring at the tyre’s inner circumference. It anchors the tyre to the rim.

Role in Tyres:

• Structural Integrity: Provides a rigid base for mounting.
• Strength Under Pressure: Helps the tyre withstand internal air pressure without slipping off the rim.
• Driving Stability: Maintains shape and performance during high-speed or sharp cornering.

Types of Bead Wire:

Some advanced tyres use bronze-coated steel bead wires for better bonding with the rubber.

 

5. Other Chemicals and Additives (5–10%)

This category includes a wide range of chemicals used to modify performance, process ability, and lifespan. These include:

(A) Accelerators:

• Speed up the vulcanization process.
• Ensure the rubber sets quickly and evenly.

(B) Antioxidants:

• Prevent the rubber from degrading due to oxygen exposure.
• Extend tyre life.

(C) Antiozonants:

• Prevent cracking caused by ozone exposure.
• Important for outdoor performance.

(D) Sulfur:

• Central to the vulcanization process.
• Cross-links rubber molecules to form a solid structure.

(E) Plasticizers and Oils:

• Improve flexibility and workability of the rubber.
• Adjust performance based on temperature and road conditions.

(F) Resins and Silica:

• Enhance wet traction and fuel efficiency.
• Often used in place of carbon black in “green” or low-rolling-resistance tyres.

These chemicals are usually present in small percentages but have a massive impact on tyre performance.

 

Ingredient Role Summary Table

Ingredient	Primary Function	Secondary Benefits
Natural Rubber	Flexibility, Grip	Shock absorption
SBR	Durability	Abrasion resistance
PBR	Wear resistance	Low rolling resistance
Carbon Black	Reinforcement	UV protection
Bead Wire	Structural strength	Rim retention
Additives	Vulcanization, protection	Longevity, efficiency

 

How Ingredient Ratios Vary with Tyre Types

Tyres aren’t one-size-fits-all. A motorcycle tyre doesn’t have the same ingredients as a mining truck tyre. Here's how compositions may shift:

Passenger Car Tyres:

• More balanced mix of NR and SBR.
• Focus on comfort, wet grip, fuel efficiency.

Truck and Bus Tyres:

• Higher natural rubber and carbon black content.
• Designed for durability and load-bearing.

High-Performance Racing Tyres:

• Greater use of synthetic rubbers and silica.
• Maximum grip and heat tolerance.

Two-Wheeler Tyres:

• Lower steel content.
• High proportion of NR and PBR for flexibility and grip.

 

The Magic of Vulcanization

Let’s not forget vulcanization — the process that transforms raw rubber into a usable tyre. This chemical process (usually involving sulfur and heat) links rubber molecules, improving:

• Elasticity
• Heat resistance
• Strength
• Rebound capacity

Without vulcanization, a tyre would be soft, sticky, and unfit for the road.

 

The Economics of Ingredient Use

Choosing how much of each ingredient to use isn't just about science — it's also about cost. Here’s how different components compare economically:

• Natural rubber: Expensive but essential.
• SBR/PBR: Cheaper synthetic alternatives, customized to performance needs.
• Carbon black: Economical filler and essential for strength.
• Steel wire: Adds cost but necessary for high-load and high-speed tyres.
• Additives: Low-cost per unit but significant in long-term performance.

Manufacturers must strike a balance between performance, cost, and longevity while meeting safety and environmental regulations.

 

Conclusion: A Tyre is More Than Just Rubber

Next time you look at a tyre, remember — it’s a product of engineering, chemistry, and performance testing. Each ingredient, from natural rubber to steel bead wire, plays a unique and important role. Their precise combination affects everything from how your vehicle handles to how fuel-efficient it is.

Whether you’re a tyre professional, a curious learner, or someone looking to buy a new set of tyres, understanding the ingredients inside can help you appreciate what makes tyres such crucial safety components.

Disclaimer:

The ingredient percentages shared in this blog are approximate and may vary slightly depending on the type of tyre (car, truck, bike, off-road), brand, and intended use (performance, economy, winter). The chemical formulations used in tyres are often proprietary and closely guarded by manufacturers. This post is based on industry research, public technical data, and typical tyre formulations