When it comes to your vehicle, understanding tyre sizes is crucial for safety, performance, and maintenance. Regardless if you're operating an SUV or a small car, the appropriate tyre size guarantees optimal traction, control, and fuel economy.
Let's break down what tyre sizes mean and how to choose the right ones for your vehicle.
Decoding Tyre Size Information
When looking at a tyre, you'll notice a combination of numbers and letters imprinted on the sidewall. Tyre sizes are denoted by a string of characters, such as 225/50R17. Each segment of this code provides specific information about the tyre's dimensions and characteristics.
Aspect Ratio and Width
The first number (225) represents the tyre's width in millimeters from sidewall to sidewall. Following the slash, the second number (50) is the aspect ratio, indicating the height of the tyre's sidewall expressed as a percentage of the width. A lower aspect ratio typically means better handling at the expense of comfort, as the tyre has a shorter sidewall.
Construction Type
After the aspect ratio, there's a letter that identifies the tyre's construction. The letter (R) stands for radial, which is the construction method used in most modern tyres. You may sometimes also see a 'D' for diagonal or bias-ply tyres, which are less common and generally used for specific types of vehicles or trailers.
Wheel Diameter
The last number (17) is the size of the wheel that the tyre is designed to fit. This is measured in inches and it's important to match this number with the size of your car's wheels.
Load Index and Speed Rating
Following the basic size specifications, there may be a space and then a number with a letter. These indexes indicate the maximum speed and load capacity that the tyres can safely handle.
The speed index is represented by a letter (e.g., H, V, W) which relates to the maximum speed at which the tyre can carry a load corresponding to its load index.
On the other hand, the load index is a numerical value which indicates how much weight the tyre can support when properly inflated.
