Detailed Meaning Of The Numbers On The Car Tyre. Did You Know?

On every tyre’s side, especially, on the reputed tyre brands such as Michelin, Bridgestone, there's always a set of numbers and letters which are formatted in code. These codes contain a massive amount of information which speaks up: 

• The tyre purpose

• The radial construction

• The total load

• The weight capacity

• The dimensions

• The speed rating

Most of the tyres will have something similar like this printed on the side of it:

For example, P185/75R14 82S

 Every tyre will have an expansion of numbers and letters

1. The first letter means the type of tyre for certain vehicles

P = Passenger vehicles tyre. The "P" letter at the beginning indicates that the tyre is a P-Metric tire. It refers to the tires made with some certain standards, intended for the passenger vehicles. If a tire has no letters at the beginning, it is sure a Euro-metric tire. P-Metric and Euro-Metric tires may have different load capacities.

T = Truck vehicles tyre/ LT = Light truck vehicles tyre. Many vehicle manufacturers equip for some light trucks with "LT" type tyres. These tyres basically require a higher inflation pressure than passenger tire.

2. The 3 digit number (185) is the Width

This number refers to the width in millimetres. The measurement distance in millimetres is from the maximum width of the tyre’s midpoint of its sidewall to the same point on the opposite sidewall.

3. The 2 digit number (75) is the Aspect Ratio

It is the ratio of the height of the tyre’s cross-section expressed as a percentage of the tyre’s section width. The number 75 means that the height is equal to 75% of the width of the tyre which is 75% x 185 = 138.75mm.

These are the width, height, rim diameter of the tyre

4. The letter (R) stands for Radial in the Construction Code

This means the layers run radially across the tyre. R indicates that the tyre is manufactured with a radial ply construction.

The number (14) is Wheel Diameter as known as rim diameter.

This number presents the size of the wheel which measured from one end to the other. It implies the size of the wheel (or rim) to know exactly which type is intended to fit on.

The next number (82) is the Load Index.

Load Index indicates the maximum load that the tyre can support when it is inflated properly. The maximum load on the tyre sidewall would be found out on the tyre sidewall in both LBS pounds and KG kilograms.

5. The last code which is the letter (S) identifies the Speed Rating

The speed rating is in charge of showing the maximum speed capability of a tyre. A tyre with an S speed rating has a maximum speed capability of 180 kmph.

There are also other letters which identify the speed rating.

M = 130 kmph

N =140 kmph = Spare Tyres

P = 150 kmph

Q = 160 kmph = Winter Tyres

R = 170 kmph = Truck Tyres

S = 180 kmph = Cars and Minivans

T = 190 kmph = Cars and Minivans

U = 200 kmph = Sport Performance Cars

V = 240 kmph = High Performance Cars

W = 270 kmph = Ultra High-Performance Cars

Y = 300 kmph = Ultra High-Performance Cars

Now you nailed all the meanings on the car tyres yet? Make sure the answer is yes to understand more about tyres which helps to replace the old tyre with a suitable one.

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How to Read a Tire Size & Understanding a Tire Sidewall

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