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Buying Tyres Guide: What Do Tyre Numbers Mean and Why Do They Matter?

Knowing the numbers on your tyres is crucial to maintaining the safety and performance of your vehicle.

Tyre Number System

The tyre number system is a mixture of letters and numbers that offer information about the tyre’s type, breadth, aspect ratio, construction type, diameter, load index, and speed rating.

    Here is a breakdown of the Tyre number system:

  1. A. Rim Diameter
    1. 1. The two-digit value reflects the rim diameter in inches.
    2. 2. Common measurements include 8”, 10”, 12”, 13”, 14”, 15”, 17”, 18”, 19”, 20”, 22”, 23”, 24”, 26”, and 28”.
  2. B. Service Type
    1. 1. The letter or vacant space before the rim diameter denotes the tyre’s service type.
    2. 2. P is for P-metric passenger vehicles, no letter is for metric-sized tyres, and LT is for light trucks.
  3. C. Aspect Ratio
    1. 1. The middle value indicates the tyre’s aspect ratio, which is the tyre height measured from the cross-section to the breadth.
    2. 2. The aspect ratio influences the tyre’s performance, with broader sidewalls offering higher travel comfort and narrower sidewalls providing better control.
  4. D. Tyre Construction
    1. 1. The optional code for the manufacturer incorporates the category of the tyre, its structure, and tread pattern.
    2. 2. The code is vital for tyre recalls, and you may verify whether your tyre model has been recalled.
  5. E. Load and Speed Ratings
    1. 1. The load index indicates how much weight the tyre can safely manage.
    2. 2. The speed indication specifies the maximum speed a tyre is intended to travel.

To establish the utmost load and speed of a tyre, you may refer to the load index and speed symbol. The treadwear rating is also crucial for tyre durability, and the production date code helps establish the age of the tyre. Understanding these values is vital for choosing the correct tyre for your vehicle.

Treadwear Rating

The Treadwear rating is a figure that reflects the projected life of a tyre, whereas the tread rating pertains to the pattern on the tyre. The treadwear rating varies from 100 to 500, with greater values suggesting longer-lasting tyres. The classification is established by evaluating the tyre against a control tyre after being driven 7,200 miles on a government test track.

The grade is an indication of the tyre’s durability, but it’s not fixed in stone and may fluctuate owing to external influences. tyres’ treadwear values are evaluated in controlled situations, and outside conditions, driving habits, and road hazards may decrease or prolong the actual tread life. Understanding the treadwear rating is vital for tyre life and helps assess the value of a tyre.

Tyre Age

The production date code is a four-digit number which is inscribed on the tyre that indicates the week and year of manufacture. The final four numbers in the series are essential, because the first two numerals denote the week and the last two represent the year. This enables you to determine the production month and year of your tyres.

The age of the tyre is significant since rubber dry rots with time, and may become fragile and hazardous. Tyres that are more than six years old should be evaluated by a professional and changed if required.


Understanding tyre numbers is vital for choosing the proper tyre for your vehicle and maintaining maximal performance and safety. The tyre number system incorporates the rim diameter, service type, aspect ratio, tyre construction, and load and speed ratings.

The treadwear rating is vital for tyre durability, and the production date code helps estimate the age of the tyre. Evaluating the projected tread life and warranty of various tyre types will help you select car tyres that provide a suitable combination of durability and handling. Always examine the production date code to substantiate that the tyres are not too old and have not surpassed their expiry.

By knowing Tyre numbers, you can make right selections when selecting Tyres and ensure that your car is safe and operating at its best.

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