Find Your Fit: Tyre Size Chart Explained

Understanding your tyre size is crucial when it comes to finding the perfect fit for your vehicle. The markings on the sidewall of your tyre provide important information about size, load, and more. You can refer to the tyre placard or your vehicle’s user manual for the recommended tyre sizes. The tyre size is typically indicated by the section width, sidewall height, and rim diameter. It is important to choose the right tyre size to ensure your vehicle remains roadworthy and safe. You can also use a tyre size calculator to determine the right fit for your vehicle.

Key Takeaways:

  • Tyre size is essential for finding the perfect fit for your vehicle.
  • The markings on the tyre sidewall provide important size and load information.
  • Refer to the tyre placard or user manual for recommended tyre sizes.
  • Choose the right tyre size based on section width, sidewall height, and rim diameter.
  • Use a tyre size calculator for accurate measurements.

How to Read Tyre Size Markings

Tyre size markings can be confusing if you’re not familiar with them. Understanding these markings is essential for comparing tyre sizes, converting sizes, and finding the right tyre for your needs. Here’s a breakdown of how to read tyre size markings:

Section width: The section width indicates the width of the tyre in millimetres. It is measured from one sidewall to the other. For example, if the section width is 205mm, it means that the tyre’s width is 205 millimetres.

Sidewall height: The sidewall height is expressed as a percentage of the section width. It represents the height of the tyre from the base of the tread to the rim. For instance, if the sidewall height is 55% and the section width is 205mm, it means that the sidewall height is 112.75mm (55% of 205mm).

Rim diameter: The rim diameter is the size of the wheel rim in inches. It is the diameter of the circle formed by the bead seats of the tyre on the wheel rim. For example, if the rim diameter is 16 inches, it means that the wheel rim is 16 inches in diameter.

These three measurements make up the basic tyre size. Additionally, tyre markings also indicate the load capacity and speed rating of the tyre, which are crucial factors to consider for safe operation.

Marking Measurement
205 Section Width (mm)
55 Sidewall Height (% of section width)
R16 Rim Diameter (inches)

Now that you know how to read tyre size markings, you can confidently navigate the world of tyre sizes, comparisons, conversions, and finding the perfect fit for your vehicle.

Understanding Load Index and Speed Symbol

When it comes to choosing the right tyres for your vehicle, two important factors to consider are the load index and speed symbol. These markings provide crucial information about the maximum weight capacity and safe operating speed of a tyre.

The load index is represented by a numerical value that corresponds to a specific weight capacity per tyre. This value indicates the maximum load that the tyre can carry. The higher the load index, the greater the weight capacity of the tyre.

The speed symbol, on the other hand, is represented by a letter and denotes the maximum safe speed at which the tyre can be operated. The speed symbol is an indicator of the tyre’s ability to dissipate heat generated during high-speed travel. Tyres with higher speed symbols are designed to handle faster speeds.

To ensure safe and optimal performance, it’s important to choose tyres with the appropriate load index and speed symbol that match the requirements of your vehicle. Using tyres with the wrong load index or speed symbol can compromise safety and handling, and may even lead to tyre failure.

To help you understand the capacity and limitations of different tyre options, you can refer to load index and speed symbol charts provided by tyre manufacturers. These charts provide detailed information about the load capacities and speed ratings for various tyre sizes and types.

Remember, selecting tyres with the right load index and speed symbol is essential for maintaining the safety and performance of your vehicle on the road.

tyre load rating and speed symbol

Different Types of Tyres and Their Specifications

When it comes to tyres, there are various types available, each with its own unique specifications. Understanding these types can help you make an informed decision when choosing the right tyres for your vehicle and driving needs.

The most common type of tyre construction is radial ply, indicated by the letter “R”. Radial ply tyres are widely used for passenger vehicles due to their durability, performance, and comfortable ride. These tyres are designed with layers of cords that run perpendicular to the tread, providing excellent stability and traction.

If you’re looking for added safety and peace of mind, run-flat tyres are a great option. These tyres are specifically designed to allow you to continue driving even after a puncture, giving you sufficient time to reach a service station safely. Run-flat tyres are equipped with reinforced sidewalls that can support the weight of the vehicle even when the tyre is deflated.

For those who have heavy-duty vehicles, such as vans or trucks, commercial tyres are the ideal choice. These tyres are designed to withstand the demanding conditions of commercial use, offering enhanced durability, load-carrying capacity, and improved traction.

Light truck tyres, also known as LT tyres, are specially designed for light trucks and SUVs. These tyres have a higher carrying capacity than passenger car tyres and are suitable for off-road adventures, towing, and hauling heavy loads.

If you drive a Mercedes-Benz, you can opt for Mercedes Original Equipment (MOE) tyres. These tyres are specifically engineered to meet the high-performance standards set by Mercedes vehicles. They offer excellent handling, comfort, and safety, ensuring a smooth and enjoyable driving experience.

Choosing the right type of tyre is essential to maximize the performance, safety, and longevity of your vehicle. Consider your driving needs, vehicle specifications, and the specific benefits and limitations of each type of tyre when making your decision.

tyre construction

Type of Tyre Construction Benefits Limitations
Radial Ply Tyres Layers of cords running perpendicular to the tread Excellent stability and traction N/A
Run-Flat Tyres Reinforced sidewalls Ability to drive even after a puncture May have reduced handling capabilities
Commercial Tyres Durable construction Enhanced durability and load-carrying capacity Slightly less comfortable ride compared to passenger tyres
Light Truck Tyres Sturdy construction Higher carrying capacity and off-road capabilities May result in a slightly harsher ride
Mercedes Original Equipment (MOE) Tyres Engineered for Mercedes vehicles Optimized performance and safety Designed specifically for Mercedes models

By choosing the right type of tyre construction, whether it’s radial ply, run-flat, commercial, light truck, or MOE tyres, you can ensure that your vehicle performs at its best and suits your specific driving needs.

Where to Find Your Tyre Size and How to Choose the Right Tyres

Finding the right tyre size for your vehicle is essential to ensure optimal performance and safety. You can easily locate your vehicle’s recommended tyre size in two common places:

  1. In your user manual: Your vehicle’s user manual provides detailed information about the recommended tyre size. Refer to the “Tyre Specifications” section or use the index to quickly find the relevant pages. This information includes the tyre width, aspect ratio, rim diameter, load index, and speed symbol.
  2. On the tyre placard: The tyre placard is usually located on the driver’s door opening or inside the fuel filler cap. It displays crucial information about your vehicle’s tyre size and other specifications. Look for a sticker or metal plate with the tyre size markings. Pay attention to the tyre width, aspect ratio, rim diameter, load index, and speed symbol indicated on the placard.

Once you have obtained the correct tyre size, it’s important to choose the right tyres that match these specifications. Here are some tips to help you make the best selection:

  • Use a tyre size calculator: If you’re unsure which tyre size is suitable for your vehicle, you can use a tyre size calculator. These online tools allow you to input your current tyre size or vehicle details to determine the correct tyre size. Simply enter the required information and the calculator will provide you with the recommended tyre size options.
  • Consider driving conditions: Different tyres are designed to perform optimally in specific road and weather conditions. If you frequently drive on wet or snowy roads, consider tyres with enhanced traction and grip. If you primarily drive on highways, look for tyres that provide a smooth and quiet ride. Assess your typical driving conditions to choose tyres that are well-suited for your needs.
  • Evaluate your vehicle type: The type of vehicle you own can also influence the tyre selection process. For example, if you drive a light truck or commercial vehicle, you may require specific tyres designed for heavy-duty purposes. Similarly, if you own a luxury vehicle like a Mercedes, you may want to consider Mercedes Original Equipment (MOE) tyres for optimal performance and compatibility.
  • Personal preferences: Your own preferences and requirements should also be taken into account. If you prioritize fuel efficiency, look for tyres with low rolling resistance. If you prefer a sportier driving experience, consider tyres with excellent handling capabilities. Additionally, factors like brand reputation, warranty, and price can also play a role in your decision-making process.

By following these guidelines and conducting thorough research, you can confidently select the right tyres that not only fit your vehicle correctly but also meet your individual needs and preferences.


Understanding tyre size and its associated markings is crucial for finding the right fit and ensuring optimal performance for your vehicle. By referring to the tyre size chart and consulting your vehicle’s specifications, you can confidently select the correct tyre size. Pay close attention to the section width, sidewall height, rim diameter, load index, and speed symbol when choosing tyres, as these factors determine compatibility and safety.

Additionally, considering other factors such as tyre construction, vehicle type, and intended usage will further assist in making the right tyre selection. Different types of tyres, including run-flat tyres, commercial tyres, light truck tyres, and Mercedes Original Equipment (MOE) tyres, offer specific benefits for various needs.

To ensure a smooth and informed tyre selection process, you can seek guidance from a tyre professional and utilize online resources. With their expertise and the availability of a tyre size calculator, you can confidently find the perfect set of tyres for your vehicle. Remember, choosing the right tyre size and specifications is essential for a safe and enjoyable driving experience.


What information can I find on the sidewall of my tyre?

The sidewall of your tyre provides important information about size, load, and more. It includes the tyre size, load capacity, speed rating, and other specifications.

How do I read tyre size markings?

Tyre size markings can be confusing if you’re not familiar with them. The section width indicates the tyre’s width in millimetres, the sidewall height is expressed as a percentage of the section width, and the rim diameter indicates the size of the wheel rim in inches.

What do load index and speed symbol mean?

The load index indicates the maximum load a tyre can carry, while the speed symbol represents the maximum speed at which the tyre can be safely operated.

What are the different types of tyres available?

There are various types of tyres, including radial ply construction (used for most passenger tyres), run-flat tyres, commercial tyres for heavy-duty vehicles, light truck tyres, and Mercedes Original Equipment (MOE) tyres designed specifically for Mercedes vehicles.

Where can I find my vehicle’s recommended tyre size?

You can find your vehicle’s recommended tyre size in the user manual or on the tyre placard, usually located inside the driver’s door opening. This information includes tyre width, aspect ratio, rim diameter, load index, and speed symbol.

How do I choose the right tyres for my vehicle?

To choose the right tyres for your vehicle, you should consider the recommended tyre size, driving conditions, vehicle type, and personal preferences. Using a tyre size calculator can help you find the right fit, and consulting a tyre professional can provide further guidance.

About the Author

Brett is Darra Founder Kevin's son. He grew up over the past 30 years of owning Darra and before that his whole life of Kevin being around trucks, transport and everything mechanical. So whilst he is not one to pick up the tools, its certainly been a big part of his life since Kevin's 'right-of-passage' was to get him to strip an old Holden straight-six 202 engine and put it back together. These days his time is spent with his 4 kids between UK, Singapore and Australia where he has a variety of businesses.