Commonly used numbers on your Toyota tyres
Understanding the most commonly used numbers on your Toyota tyres
We often pay little attention to vehicle tyres, yet they provide the contact between your Toyota and the road and are considered a primary part of your Toyota’s safety equipment.
Unfortunately, buying tyres is often considered a grudge purchase and many people will try and find the cheapest tyres on the market to try and save costs. While it is a good habit to shop around for the best possible prices, you should consider more than just the selling price when you fit new tyres to your Toyota.
Understanding the most common numbers and symbols
A tyre’s sidewall is filled with different numbers and figures. These all have a meaning and you should heed the most important codes on the tyre of choice to make sure you buy tyres that are suited to your Toyota.
The most common number that people often refer to, is the tyre size. It is normally presented in a format similar to this: 205/60R15.
Of these letters, the first (205 in our example) is the width of the tyre in millimetres. In this case, it means that the tyre is 205 mm wide (or 20.5cm). A manufacturer like Toyota will test different tyres, sizes, compounds and tread patterns to find a specific tyre that suits the type of vehicle best.
The second figure is the height of the tyre, presented as aspect ratio of the width of the tyre. In this case the second figure (60 in our example) means that the tyre is 60% as high as it is wide (or 123 mm in our example). You would look for this aspect ratio to determine if your Toyota is fitted with low-profile or high-profile tyres. An aspect ratio of 50% or less means that the tyre has a low profile, which is often preferred on performance vehicles.
If you fit tyres that have a lower profile than the ones prescribed by Toyota during manufacturing, it will affect your Toyota’s ride quality. A low-profile tyre might look better than the high-profile tyre originally fitted to your Toyota, but it will lead to a bumpier ride (there is, after all, less cushioning in a low-profile tyre) and it may be more prone to damage if you hit a pothole.
In the same way, choosing a much wider tyre to the one that your Toyota was originally fitted with could negatively affect the steering quality. It may also affect the working of the speedometer in some vehicles, since the speedometer is calibrated to the overall circumference of the tyre. This could lead to incorrect speed readings on your speedometer, especially at higher speeds.
After the letters that indicate your tyres’ width and height, you will find a letter. This is normally an R, which means that the tyre is a radial tyre.
Radial tyres are fitted with cord plies (a type of heavy duty cord) that are embedded below the running surface of the tyre. These fibres are normally placed perpendicular to the direction of travel and it makes the tyre much safer and much less prone to bursting.
While all approved tyres are radial, you may find some budget or grey imported tyres that are not. Do not fit these tyres to your vehicle as the lack of radial support greatly reduces durability and severely affects the vehicle’s safety.
The last number in that sequence (15 in our example) refers to the diameter of the wheel rim in inches. In this example, your Toyota’s wheel rim is 15 inches.
Some people may opt to fit bigger wheel rims to their Toyota. This is usually for cosmetic purposes, but it has some impact on your choice of tyre, your vehicle’s ride and handling and the performance of certain vehicle instrumentation.
Keep in mind that a smaller diameter rim can fit a wheel with a bigger sidewall. If, for instance, you own a Toyota Hilux, Fortuner or Land Cruiser 4x4, then you may prefer to fit a wheel with a bigger sidewall for better off-road performance. Similarly, you may opt for a bigger sidewall if you own a Toyota Quantum or Ses’fikile, as a bigger tyre can absorb more of the road irregularities and ensure a more comfortable ride inside the cabin.
As always, your friendly Automark or Toyota dealer will have all the specialist knowledge and a complete reference guide to which tyres are best suited to your Toyota. Many dealers will also be able to fit tyres for you when you book your Toyota in for its next service.