Essential Tyre Size Guide for Beginners

There are several reasons why you would want to get new tyres for your car. Depending on your requirements, tyres come in a variety of sizes and categories.

In this article, we’ll explain how to tell what size tyres you’ve got on your car. This is an important thing you need to know when the time comes to replace your tyres.

Each tyre has a size written on its sidewall, on which you can also find other information, such as; pattern, brand, and more.

Reading the size of your tyres

At first glance, you might think that all tyres are the same, but they come in a wide range of sizes and tread patterns. One size won’t fit all models, makes and applications.

The size of a tyre is usually the most visible indication you can find on the side of the tyre, after the manufacturer and model.

To make things easy, there are international standards that dictate how the information of your tyres is displayed, and generally the size labelling is written in a standardised way.

The size of a tyre consists of a group of numbers and letters. For example, for the size label 285/70R17 116/113S, we are looking at the following:

• 285 is the width of the tyre in millimetres, known as the section width. This measurement is taken from the widest point of its outer sidewall to the widest point of its inner sidewall.
• 70 is the height of the tyre sidewall represented as a percentage of the width. It is also known as the aspect ratio or profile. In this case, the tyre has an aspect ratio of 70, which implies that its height is equal to 70% of 285mm, or around 199.5mm.
• R refers to the internal construction and stands for Radial.
• 17 is the diameter of the wheel rim measured in inches. The wheel diameter and the tyre must match before the tyre is mounted on the wheel.
• 116/113 is the maximum weight the tyre can carry. It is known as the load rating. In this case, the tyre has two load ratings, for when used on a dual-tyre axle.
• S refers to the tyre’s speed rating, which is represented by a letter. This is the highest speed a tyre can reach when loaded to its maximum capacity.

What is the tyre load index?

An often misunderstood component of tyre labelling is the tyre load index. All vehicle manufacturers will have information on the tyre placard that states the maximum load allowed before you compromise the efficiency and safety of your vehicle.

For example, accidentally exceeding the maximum load or speed indicated in your tyres can potentially result in the tyre overheating, possibly leading to blowouts or catastrophic loss of control.

The team at Tyres R Us will ensure your new tyres meet or exceed your factory requirements.

Your local tyre experts

Here at Tyres R Us, we are your local automotive tyre, mechanical and trailer experts servicing Sunshine and the surrounding region including Sunshine, Sunshine North, Avondale Heights, Keilor East, St Albans, Ardeer and Kealba.

You can find our workshop at 122 Munro Ave, Sunshine with convenient access and easy parking. Phone us on 03 9362 1611 to book your vehicle to see us, today!