What are those hieroglyphs on tyres?

You’ve probably seen it, the numbers and letters etched onto tyre sidewalls. But what do they mean and how does it benefit you to know?

Well to answer the first question, it’s the tyre’s measurement and specification. Think of how a tailor measures your size, it's similar for tyres as tyre sizes are rather specific.

Let’s use the above's tyre, 255/40 R21 Y XL as example. 

255 is the width in millimeters (mm). 

40 is the thickness of the side profile using a percentage of the width (in this case is 40% of 255 mm). 

R denotes a radial construction (not particularly important to know). 

21 is the diameter of the rim in inches. 

XL indicates Extra Load, which means it is able to carry heavier load than its size would suggest and is usually fitted on high-end cars. 

And Y is the speed rating, in this case Y means it’s tested at speeds up to 300 km/h.

There’s also a four-digit DOT code which indicates the year of manufacture. Using the example earlier, it states 0118. 01 indicates 1st week while 18 indicates year. This means that the tyre is manufactured in the 1st week of 2018.

Knowing this helps when you’re surveying the market for prices. Just type in your tyre specification and check out the prices from online sellers, you’ll get an idea of the price range for a specific brand and size. That way if you do head to any tyre shop, you’ll know if they’re overpriced.

As for the year of manufacture, you are able to see for yourself when the tyre was made and without having to take the seller's word for it. It also helps when you're looking to buy a used car and you want to find out the tyre's age.