Tyres are an essential component of any vehicle, and it's essential to know how to read tyre size. It helps you in selecting the ideal tyres for your car or replacing the old ones with new ones. Tyres come in a variety of sizes and specifications, and understanding the meaning behind the codes and numbers can help you make informed decisions. In this article, we will help you learn how to read tyre size to make better choices for your vehicle.
Understanding Tyre Size
Tyre size is one of the essential parts of purchasing or replacing a tyre. Tyre size consists of a sequence of numbers and letters that denote the dimensions and features of the tyre. The sequence can be found on the tyre's sidewall, and it's vital to understand the order of the numbers to find the correct tyre size. Below is the sequence of the tyre size with an explanation of each number:
- Tyre Width: The first three-digit number in the sequence is the tyre width, measured in millimetres from one sidewall to the other when the tyre is mounted and inflated correctly.
- Aspect Ratio: The next two-digit number denotes the aspect ratio, which is the tyre's height from the rim's base to the tread's top. The ratio is in percentage and is calculated by dividing the tyre's height by the width.
- Construction Type: The next letter in the sequence represents the construction type. Here are the three types of construction:
- R: Radial construction
- B: Belted bias construction
- D: Diagonal bias construction
- Rim diameter: The next two-digit number is the rim diameter, which is the measurement from one end of the wheel rim to the other. It is measured in inches.
- Load Index: The number that comes after the rim diameter is the load index. It suggests the maximum load that the tyre can carry in pounds or kilograms.
- Speed Rating: The final letter in the sequence denotes the speed rating, which is the maximum speed at which the tyre can operate safely.
Example Tyre Size
To understand tyre size better, let's take an example. Suppose the tyre size sequence on the sidewall is P215/65R15 95H; the code means the following:
- The tyre width is 215 millimetres
- The aspect ratio is 65 percent of the tyre width
- The construction type is radial (R)
- The rim diameter is 15 inches
- The load index is 95, meaning the tyre can carry up to 690kg (1521 lbs)
- The speed rating is H, meaning the maximum speed the tyre can handle safely is 130 mph
Final Thoughts
Knowing how to read tyre size is essential when it comes to purchasing or replacing tyres for your car. It's always safer to stick with the manufacturer's recommendations or consult a professional for guidance. Remember to check your tyre's size and specifications before purchasing or replacing, as fitting the wrong tyre size can have adverse effects on your car's handling and safety.
