How to Read Tyre Sidewall Markings

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Comments 35
29 Jun 2026

Your Tyre's Sidewall Is a Data Sheet

Most drivers glance at their tyres only to check for obvious damage or to kick them. But those raised letters and numbers on the sidewall are a complete specification. They tell you the tyre's size, its load-carrying capacity, its maximum speed, and even the week it was made. Learning to read them takes five minutes and can save you from buying the wrong replacement, running dangerous pressures, or fitting a part-worn tyre that is older than you think. Here is what to look for.

Reading the Size: Width, Profile and Rim

The biggest string of characters is the size. A typical marking looks like 205/55 R16. Here is how it breaks down:

205 – the tyre's section width in millimetres, measured from sidewall to sidewall at its widest point.
55 – the aspect ratio. This is the sidewall height as a percentage of the width. So 55 means the sidewall is 55% of 205mm, or about 113mm tall. A lower number means a shorter, stiffer sidewall and usually sharper handling but a firmer ride.
R – radial construction. Almost every modern car tyre is radial. You might also see a "ZR" on high-performance tyres, but that is a historical speed-related marking.
16 – the rim diameter in inches. This tyre fits a 16-inch wheel.

If you change any of these numbers, you change the tyre's rolling radius. A larger overall diameter will make your speedometer read low and can foul suspension or bodywork. If you want a different size, keep the overall diameter within about 2% of the original and check clearance.

Load Index and Speed Rating

Straight after the size you will often see two more characters, such as 91V. The number is the load index. It is a code for the maximum weight the tyre can carry when inflated to the correct pressure. 91 means 615kg per tyre. The letter is the speed rating: V means the tyre is rated for up to 149mph (240km/h).

Never fit a tyre with a lower load index or speed rating than the vehicle manufacturer specified. Your handbook, the door pillar sticker, or the fuel filler flap will list the original figures. A higher load index is safe but can make the ride harsher because the sidewall is reinforced. A higher speed rating is also safe for road use, though it may cost more and wear slightly faster.

Common load indices: 84 = 500kg, 88 = 560kg, 91 = 615kg, 94 = 670kg.
Common speed ratings: T = 118mph, H = 130mph, V = 149mph, W = 168mph, Y = 186mph.

The Date Code: How Old Is Your Rubber?

On one sidewall only, you will find a code beginning with DOT (or just the last four digits). The final four numbers are the date of manufacture. For example, 2219 means the tyre was made in week 22 of 2019. The first two digits are the week (01–52), the last two are the year.

Rubber ages even if the tread looks fine. UV light, ozone, and repeated heat cycles cause the compound to harden and crack. Most manufacturers suggest replacing tyres at six to ten years old, regardless of tread depth. For caravans, trailers, and spare wheels that sit outside, five to seven years is a safer limit. If you are buying part-worn tyres, always check the date code and walk away from anything older than five years.

Other Markings Worth Knowing

Sidewalls carry more than just size and date. Here are the ones that matter:

M+S – mud and snow. This is a self-declared marking and does not guarantee winter performance.
3PMSF (a three-peak mountain snowflake symbol) – a proper winter tyre that meets European snow traction standards.
E-mark – a circled E with a number, showing the tyre meets European safety regulations. Required for road use.
Max pressure – the highest pressure the tyre can safely hold, often 44psi or 50psi. This is not the pressure you should run. Use the vehicle manufacturer's recommendation.
Treadwear, traction and temperature – a three-digit number and two letters, usually on the inner sidewall. Treadwear 300 means roughly three times the wear resistance of a reference tyre, but it is not a direct lifespan measure.
Tubeless or tube type – tells you whether the tyre needs an inner tube. Modern car tyres are almost all tubeless.

Putting It Into Practice

Now that you can read the sidewall, use it. When buying replacements, match the size, load index, and speed rating to the original. Check the date code before the fitter mounts the tyre. For pressures, ignore the max pressure on the sidewall and use the car's cold inflation figures, adjusting for heavy loads or sustained high speeds. Buy a decent pressure gauge and check when the tyres are cold – before a journey, not after. If you change to a different tyre size, you may need different pressures; ask a professional for a starting point.

Finally, remember that the sidewall is also a wear indicator. Look for small raised bars in the main tread grooves. If the tread is level with them, the tyre is at 1.6mm and illegal for road use. Many drivers replace at 3mm for better wet grip. Reading the sidewall will not make you a tyre engineer, but it will help you make safer, smarter choices every time you park up in the garage.

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5 Comments

Robert Sonny says Jul 21, 2024 at 10:00am

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- John Abraham says Jul 21, 2024 at 10:00am
  
  I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
  Reply
  - Robert Sonnysays Jul 21, 2024 at 10:00am
    
    I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
    Reply
Robert Sonny says Jul 21, 2024 at 10:00am

I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system
Reply

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