Índice
What are tyre markings and why do they matter?
Tyre markings are the set of alphanumeric codes found on the sidewall of every tyre. These numbers and letters contain all the essential information about its characteristics: dimensions, load capacity, maximum speed, date of manufacture and much more. Knowing how to read and interpret these codes is key to ensuring your vehicle's safety and performance.
There are several important reasons to understand them:
- Safety: You can be certain you're fitting the right tyres for your vehicle, ensuring optimal grip, braking and stability.
- Performance: Choosing the right tyre has a direct impact on how your car handles and how much fuel it consumes
- Legal compliance: Fitting tyres that don't meet the required specifications or that fall below the approved ratings can result in a fine and a failed MOT.
What the numbers on a tyre mean
The most visible sequence on a tyre usually looks something like 205/55 R16. This code is a core part of tyre nomenclature, and understanding what these numbers mean is key to reading your tyres correctly.
Width, profile and diameter
- 205 (Width): The first number indicates the tyre's width in millimetres. In our example, the tyre is 205 mm wide. A wider tyre generally provides more grip on dry roads, but can be less effective in wet conditions.
- 55 (Profile): This is the height of the tyre's sidewall, expressed as a percentage of the width. Important: this is not 55 millimetres — it's 55% of 205 mm. A lower profile delivers sharper, more responsive handling, while a higher profile tends to offer a more comfortable ride.
- 16 (Diameter): This indicates the rim diameter in inches. It's essential that this number matches your wheel rims exactly.
Construction type
- R (Construction): The letter between the profile and diameter tells you about the tyre's internal construction. "R" stands for "Radial" — the standard construction used on virtually all modern vehicles. Its radial cord structure offers greater flexibility, durability and efficiency.
Vehicle type (P, LT, C)
Sometimes the sequence begins with a letter, which indicates the type of vehicle the tyre is designed for:
- P: Passenger vehicle (car).
- LT: Light Truck.
- C: Commercial vehicle or cargo van.
If no letter appears, the tyre is assumed to be for passenger cars (equivalent to P).
What the letters on a tyre mean
Alongside the dimension numbers, you'll also find additional codes such as 91V, which are equally important. These letters form part of the tyre's coding system and provide key information about its speed rating and other characteristics. Here's what they mean.
Speed rating
The final letter in the main sequence (the "V" in our example 205/55 R16 91V) is the speed rating. This code indicates the maximum speed at which a tyre can safely operate under its maximum load. It's vital that you never fit a tyre with a speed rating lower than the one specified by your vehicle manufacturer.
Some common examples:
- T: up to 190 km/h
- H: up to 210 km/h
- V: up to 240 km/h
- W: up to 270 km/h
- Y: up to 300 km/h
Usage symbols
We'll take a closer look at specific symbols such as M+S further below, but within the main sequence, the most relevant letters are those we've just covered. Together, these numbers and letters define the core characteristics of the tyre types you can safely fit to your vehicle.
Other important tyre codes
Beyond the main sequence, tyres carry a number of additional codes and symbols that offer genuinely useful information. These are key to understanding the full picture.
DOT code and date of manufacture
The DOT code (Department of Transportation) confirms that the tyre meets US safety standards — but the most useful part for most drivers are the last four digits. These numbers& reveal the date of manufacture: the first two indicate the week and the last two the year.
For example, 3523 means the tyre was manufactured in week 35 of 2023. This is crucial information, as it helps you determine how long the tyre has been stored or assess whether it's still in good condition.
Load index
The number that precedes the speed rating (the "91" in 205/55 R16 91V is the load index This numerical code indicates the maximum weight each individual tyre can support. Just as with speed ratings, you should never fit a tyre with a load index lowe than the one recommended by your vehicle manufacturer.
Some examples:
- 88: 560 kg
- 91: 615 kg
- 94: 670 kg
Understanding other common tyre symbols
Beyond what we've already covered, the sidewall of a tyre is home to a number of smaller symbols that reveal important details about its use and characteristics.
Yellow or red dot
These coloured dots are mounting guides used during initial fitting. The red dot marks the point of maximum radial force variation (the tyre's "highest" point), while the yellow dot marks its lightest point. They're used to balance the tyre and rim together as efficiently as possible.
Triangle or TWI
The triangle symbol — or the letters TWI (Tread Wear Indicator) — marks the location of the wear indicators within the tread. These are small rubber blocks set into the tread grooves. When the tyre wears down to the level of these indicators, it has reached the legal minimum tread depth of 1.6 mm, and it's time to replace it.
Arrow
Some tyres are directional, meaning they're designed to roll in one direction only. An arrow on the sidewall shows the correct direction of rotation. Fitting them the wrong way round would seriously compromise their performance, particularly in wet conditions.
Outside and Inside markings
Tyres with an asymmetric tread pattern have a specific outer (Outside) and inner (Inside) face. Fitting them in the correct position is essential to ensure their effectiveness in cornering and their ability to channel water away.
M+S and 3PMSF symbols
- M+S (Mud and Snow): Indicates that the tyre is designed to perform better in mud and snow than a standard summer tyre.
- 3PMSF (Three-Peak Mountain Snowflake): This is a pictogram showing a three-peaked mountain with a snowflake inside. The symbol certifies that the tyre has passed specific tests in severe winter conditions, delivering superior performance on snow and ice. If you're wondering what happens if you use winter tyres in summer, the answer is straightforward: their softer compound will wear out significantly faster in the heat.
Vehicle manufacturer symbols
Some car manufacturers work closely with tyre brands to develop versions specifically tailored to their models. These typically carry a special marking, such as "MO" (Mercedes Original), "*" (BMW) or "AO" (Audi Original).
Key takeaways
Taking everything we've covered as a reference, here's a handy summary:
Understanding tyre markings gives you the knowledge to make safer, smarter decisions for your car. At Moeve, we're with you every kilometre of the way — offering the best products and services so you can focus on what really matters: enjoying the ride.
