What Do the Numbers on Car and Bike Tyres Mean? A Complete Guide for Drivers

Have you ever noticed the numbers and letters written on the tyres of your car or bike? At first glance, they might look like random codes, but in reality, these markings reveal everything about the tyre’s identity. From width and height to construction type, rim size, load capacity, and speed rating—every detail is coded into those numbers. Understanding them is essential if you want to maintain safety, improve performance, or replace tyres correctly.

Let’s decode what these numbers and letters actually mean.

Example of Tyre Marking

You may see something like “145/80 R12 74T” or “205/65 R15 94H” written on a tyre. Each part of this sequence carries a specific meaning:

Tyre Width – The first number (e.g., 145 or 205) shows the width of the tyre in millimeters.

• Example: “145” means the tyre is 145 mm wide.

Aspect Ratio (Profile Height) – The second number (e.g., 80 or 65) indicates the aspect ratio. It tells you the height of the tyre’s sidewall as a percentage of its width.

• Example: “80” means the sidewall height is 80% of the tyre’s width.

Construction Type (R) – The letter “R” indicates Radial construction, which is the most common type today. Radial tyres are strong, durable, and widely used in both cars and bikes.

Rim Diameter – The next number (e.g., 12 or 15) refers to the diameter of the rim in inches. This ensures the tyre fits perfectly with your vehicle’s wheel size.

• Example: “R15” means the tyre fits a 15-inch rim.

Load Index – The following number (e.g., 74 or 94) indicates the maximum load capacity of the tyre. Each code corresponds to a specific weight in kilograms.

• Example: “74” means the tyre can carry about 387 kg, while “94” indicates around 670 kg (per tyre).

Speed Rating – The last letter (e.g., T, H, V) shows the maximum speed the tyre can safely handle.

• T = up to 190 km/h

• H = up to 210 km/h

• V = up to 240 km/h

Why These Numbers Matter

Knowing how to read tyre codes is more than just technical knowledge—it’s directly linked to road safety and performance. If you choose a tyre with the wrong width or rim size, it can affect handling and fuel efficiency. Similarly, exceeding the speed rating or load index can be risky, especially on highways.

For example, a tyre designed for 190 km/h (T rating) should not be pushed to 220 km/h. Likewise, overloading tyres beyond their load index can lead to blowouts.

Quick Recap of Tyre Number Meaning

• First Number: Tyre width in millimeters.

• Second Number: Aspect ratio (sidewall height as % of width).

• R: Radial construction type.

• Next Number: Rim diameter in inches.

• Load Index: Maximum load-carrying capacity.

• Last Letter: Speed rating (maximum safe speed).

Final Thoughts

Tyres are one of the most crucial parts of your vehicle, and these numbers help you choose the right ones. When replacing tyres, always ensure that the size, load index, and speed rating match your vehicle’s requirements. Doing so not only improves driving comfort and fuel economy but also ensures safety at high speeds and during heavy loads.

So, next time you look at your car or bike’s tyres, remember—they are not just numbers, but the complete identity card of your tyre.

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