Tyres bear the entire weight of the vehicle. As the parts that contact the road, the importance of them can never be overemphasized. To ensure safety and driving comfort, the correct tyres should be used. You can check your vehicle manual to find out which type fits the most and then make your choice wisely. To make sure you completely understand your tyres, we wrote this article and hope you can find helpful information.

How to find your tyre size?

Tyre size and specifications can be found on the sidewall. See the picture below.

What does this code mean?

We can see a group of codes on the sidewall of the tyres, for example 195/55R15 85V. The meaning of this code can be explained in detail.

195, the section width of the tyre in millimetres. The wider the section width, the greater the contact area between the tyre and the ground, and the better the traction.

55 is the AR, that is aspect ratio or flat ratio in %. It is the height of the sidewall divided by the tyre's width. The greater the AR, the more comfortable when driving, but the less feedback of the road condition. Conversely, the smaller the AR, the better the feedback from the road surface and the handling of the vehicle.

R stands for construction type. In this case it is a radial type. Radial tyres have a larger road contacting area, so the driving comfort is greatly improved; they generate little heat in the tyre when driving at high speed and due to steel wire sheets are added, they tend to be stronger and don’t deform much when driving, thus a lower fuel consumption and a longer service life.

15 is the rim diameter in inches. Here in this instance if converted into millimeters, the diameter of the rim is 15*25.4 equals 381mm.

85 is the tyre’s load index. It refers to the maximum load the tire can carry under some specified conditions.

The list below explains how load indices is transferred into maximum weights.

V indicates the tyre’s speed rating. All tyres have a speed symbol showing the maximum speed the tyre can work at properly. Check the table below for detailed information. To avoid standing wave phenomenon, do not drive faster than the tyre is designed to.

Standing waves phenomenon is explained here. Tyres deform due to the load’s weight. When driving faster than it’s designed maximum speed, the deformed tyre stands no time to revert to its original form, thus the standing wave phenomenon. It should be avoid as this can cause a high-speed tire blowout.

Meaning of Other Marks

M+S means mud and snow tyres. See the picture below.

Triple T index contains three indices, treadwear index, traction index and temperature index.

Treadwear index designates the tyre’s wear resistance. See the picture below for details.

Traction index shows the tyre’s group gripping capability. There are four levels, AA, A, B and C. Level AA is the highest level, C is the lowest. The higher the level, the stronger the grip.

Temperature index suggests the tyre’s heat dissipation capacity. There are three levels, A, B and C. Level A is the best.

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