How to read tyre size?
Identifying the right tyre size for your vehicle is essential. It’s not a matter of whether they look good, it’s important from a safety and drive perspective and some regulations must be followed.
You should select your new tyres according to your vehicle documents and tyre manufacturer recommendations. If you choose the wrong ones, there could be problems with ride and safety. Thankfully help is at hand from tyre specialists.
Tyres are specific sizes so if you choose the wrong ones they simply won’t fit, but there is usually a range of tyres that will fit every wheel.
Why does it matter?
For starters, mismatched tyres can interfere with the accuracy of your speedo so you may see false speed readings on your dash.
Unequal tyres can adversely affect your car’s steering, accelerating and general handling characteristics, leading to instability and safety issues.
Having mismatched tyres on your vehicle can also mean it takes noticeably longer to get up to speed and additionally, can take significantly longer to come to a safe stop.
How do you find the correct tyre size for your car?
There are several ways you can determine the size tyre you will require including in your instruction manual or vehicle documentation, within your vehicle, and on the sidewall of your current tyres.
Vehicle documentation
Your owner’s manual will have information like the size of your wheels and the size of tyre that will fit them. You might also find this information on other paperwork you received when you purchased the car. Be aware that if you purchased the vehicle second-hand it may not be fitted with the standard wheels. You may also find that the model you purchased had several options.
Inside the vehicle
Most vehicles will also have the information printed on a plate or sticker within the vehicle which you might find in the door jamb of either the driver’s or front passenger side, in the glove box, or even inside the fuel cap. Once again be aware that if the vehicle does not have the original wheels fitted, they may be a different size.
On the sidewall of the tyres
The brand, model name and tyre size are also printed on the sidewall of the tyres on your vehicle. Note down the numbers or take a photo with your phone because you’ll need all the information to identify the best options for your vehicle. Check all four tyres because they may be different from front to rear.
What do all those numbers on my tyres mean?
It might seem a little confusing at first with all those numbers, but here is a simple explanation of what they mean.
Let’s use the Solus KR21, Kumho tyre's Standard Touring All-Season tyre. On the sidewall, you will find 185/75R14 89T printed.
- 185 indicates the width of the tyre in millimetres (185 mm)
- 75 indicates its aspect ratio, a comparison of the tyre’s section height with its section width (75 indicates the height is 75% of its width)
- R indicates radial ply construction
- 14 indicates the diameter of the wheel rim (14 inches)
- 89T is a symbol indicating the maximum load capacity and speed at which the tyre can be safely operated. This is subject to the tyre being correctly fitted, in sound condition, and with recommended inflation pressures (89 can carry a load of 580 kg per tyre; T represents a maximum speed of 190 km/h).
What do I do with this information?
You can then visit websites like Kumho Tyre and use our handy Tyre selector to identify the different options.
Alternatively, you can visit the websites and outlets of Kumho’s authorised dealers who can provide advice on your options. They can then order the tyres of your choice and fit them for you. Many dealers will include fitting in the price.