How to Read Your Tyre Size: A Simple Guide for Australian Drivers

Buying new car tyres can be confusing, especially when you see numbers and letters printed along the tyre sidewall.

What does 205/55 R16 mean? What is a tyre load index? Does the speed rating matter?

These details help identify which tyres are suitable for your vehicle.

If you are shopping for new tyres in Brisbane, understanding tyre markings can help you compare options and avoid buying the wrong size.

Here is a simple guide to reading tyre sizes in Australia.

Where Can You Find Your Tyre Size?

Your tyre size is printed on the sidewall of your existing tyre.

You may see a code such as:

205/55 R16 91V

You can also check the manufacturer’s tyre placard, commonly located near the driver’s door, or consult the vehicle owner’s manual.

Remember that tyres already fitted to a used vehicle may not be the original size or an approved replacement size.

Always confirm the correct specifications for your vehicle before purchasing.

What Does 205/55 R16 91V Mean?

Let’s break down each part.

205 — Tyre Width

The first number indicates the tyre’s nominal section width in millimetres.

In this example, the tyre is 205 mm wide.

Tyre width can affect fitment and vehicle handling, so you should not change it without checking compatibility.

55 — Aspect Ratio

The second number represents the sidewall height as a percentage of the tyre’s width.

Here, 55 means the nominal sidewall height is 55% of the section width.

It does not mean the sidewall is 55 mm tall.

R — Radial Construction

The letter R means the tyre uses radial construction.

Radial tyres are widely used on modern passenger vehicles.

16 — Rim Diameter

The number 16 indicates that the tyre is designed for a 16-inch wheel rim.

The tyre and rim diameters must match.

You cannot fit a tyre intended for a 16-inch rim onto a 17-inch rim.

91 — Load Index

The number 91 is the tyre’s load index.

A standard load index of 91 corresponds to a maximum rated load of 615 kg per tyre under the specified conditions.

Different load index numbers correspond to different load capacities.

Always choose a tyre with a load rating that meets the vehicle manufacturer’s requirements and applicable regulations.

V — Speed Rating

The letter V is the tyre’s speed symbol.

It corresponds to a rated maximum speed of 240 km/h under specified conditions.

This marking is a tyre capability rating, not permission to exceed road speed limits.

The appropriate speed rating depends on the vehicle and applicable requirements.