How to read tire markings?

Symbols on tires indicate their size, load capacity, speed rating, seasonality, and production date. Thanks to them, you can choose the right model for your car and driving conditions. This is the foundation of safe use. In this article, we will explain all the issues related to tire markings.

Tire markings – what do the symbols on the sidewalls mean?

Tire size – the basis of fitment

The most visible marking on the tire is its size, e.g. 225/45 R17 94W. What do these numbers and letters mean?

The tire size is a basic piece of information found on the tire's sidewall. These markings provide us with a lot of data about the physical dimensions of the tire and its operating parameters. Understanding this notation helps avoid mistakes when buying and ensures optimal driving characteristics.

• 225 – tire width in millimeters
• 45 – aspect ratio, the percentage ratio of sidewall height to width (here: 45% of 225 mm)
• R – radial construction (currently standard in most tires)
• 17 – rim diameter in inches
• 94 – Load index (here: 670 kg per tire)
• W – speed index (here: up to 270 km/h)

📊 Tire Load Index Table

The load index indicates the maximum load that a single tire can carry at the maximum permissible pressure. The higher the index, the greater the tire's load capacity. It’s important to note: the specified value applies only when the tire is fully inflated and refers to static load, such as driving straight on a flat surface. The load index must not be lower than specified by the vehicle manufacturer

• Speed Index indicates the maximum speed a tire can maintain at its rated load. For example:
• H = 210 km/h
• V = 240 km/h
• W = 270 km/h
• Y = 300 km/h

It is good practice to choose tires with at least the same indices as specified by the vehicle manufacturer. For sports cars and heavier SUVs, differences in load and speed ratings are very important.

Homologations and manufacturer symbols – what do AO, MO, N0... mean?

When buying new tires, we often come across mysterious markings on the sidewalls – such as AO, MO, N0, RO1, or K1. What do they mean? These are manufacturer homologations – confirmation that the tire has been developed or tested specifically for a particular car brand and model.

✅ What do the most popular tire homologation symbols mean?

Check how to interpret markings like AO, MO, N0, or K1. These symbols indicate that the tire was designed or tested for specific car manufacturers.

Why does it matter?

Homologated tires feature different rubber compounds, carcass constructions, or tread patterns tailored to the needs of a particular car model. Sometimes the differences are cosmetic, but often they significantly affect:

• braking distance
• tread wear
• compatibility with suspension and vehicle electronics

If you own a Porsche 911, BMW M3, or Audi RS – it’s definitely worth choosing tires with the appropriate marking to ensure full performance and safety.

In our experience, we’ve seen cases where one axle had tires with, for example, N0 homologation, while the other had no marking or a different one, like MO. Theoretically, they matched in size but differed in performance characteristics – which in cars like the Porsche 911 can affect handling and traction systems.

Therefore, we always recommend fitting tires with the same homologation on both axles (front and rear) – even if the vehicle manufacturer doesn’t explicitly require it. It’s a simple way to avoid unexpected vehicle behavior – especially during dynamic driving.

✅ Is it always worth buying homologated tires?

• If you own a premium vehicle (Audi S/RS, BMW M, Mercedes AMG, Porsche) – definitely yes.
• For city cars you can consider non-homologated options – but always make sure the tire meets all required specifications (size, load and speed indices, construction type).

Tire type and seasonal markings – when and where to use?

Not all tires are universal. Depending on weather conditions and driving style, you should choose the appropriate tire type. Manufacturers use clear seasonal markings:

• M+S (Mud + Snow) – tire suitable for muddy and snowy conditions. It can be a winter or all-season tire, but does not always meet true winter tire standards.
• 3PMSF (Three Peak Mountain Snowflake) – a snowflake symbol on a mountain background. This is official winter certification – the tire has been tested for snow performance.
• All Season / 4-Seasons – all-season tire combining summer and winter features. Suitable for moderate climates and drivers with lower mileage.
• Summer / Winter – simple season indication. Summer tires should not be used in winter, while winter tires lose grip on dry summer roads and wear out faster.

Remember that in some countries (e.g., Germany, Austria), driving in winter without tires marked with 3PMSF may result in a fine – even if the tire has M+S marking.

Additional technical markings

In addition to basic size and seasonal data, tires also feature additional technical markings indicating construction, reinforcements, and mounting direction:

• XL (Extra Load) – tire designed for higher loads. Recommended for SUVs, station wagons, and utility vehicles.
• RF (Reinforced) – indicates reinforced construction. Often used interchangeably with XL.
• Tubeless (TL) – tubeless tire. Standard today – more airtight, safer, and easier to service.
• Rotation / Directional – indicates rolling direction. Important during installation – incorrect mounting reduces grip.
• Asymmetrical / Inside / Outside – tire with asymmetrical tread. Clearly marked inner and outer sides.

(Incorrect installation of directional or asymmetrical tires can lead to faster wear, poorer traction, and even reduced safety on wet surfaces.)

• Run Flat – allows driving after a pressure loss (usually up to 80 km at reduced speed).

EU tire label – what does it mean and why check it?

In addition to technical markings on the tire sidewalls, every new tire sold in the European Union must have an EU label. This is a sticker or store information (also online), showing three key performance parameters:

• Fuel efficiency (rolling resistance) – affects fuel consumption.
• Wet grip – directly related to safety.
• External noise level – measured in decibels and classified alphabetically.

Since 2021, labels may also include markings for winter tires (3PMSF) and ice grip (Ice Grip), if the manufacturer foresees such use. Thanks to the EU label, you can quickly compare tires not only by appearance or tread but also by real road performance. Remember – every new tire in the EU must have an EU label and product sheet, and their absence may indicate illegal import or seller error.

Key technologies used in modern tires

Modern tires are more than just rubber and tread – they are advanced engineering products utilizing innovative solutions to improve comfort, performance, and safety. Here's an overview of key technologies worth knowing before purchasing a set of tires.

Run Flat tire – what does it mean and how does it work?

Run Flat is a technology that allows continued driving even after a complete loss of pressure. This is possible thanks to specially reinforced sidewalls that support the vehicle's weight. In other words – even if you get a flat tire, you can still drive about 80–100 km at a speed of up to 80 km/h without risking immediate vehicle immobilization.

Run Flat tires have various designations depending on the manufacturer:

• RFT – Run Flat Tire (Bridgestone, Dunlop)
• SSR – Self Supporting Runflat (Continental)
• ZP – Zero Pressure (Michelin)
• EMT – Extended Mobility Tire (Goodyear/Dunlop)
• ROF – Run On Flat (Goodyear)
• MOE – Mercedes Original Extended (for Mercedes models)

🚗 Run Flat vs. conventional tire – comparison

Check the key differences between Run Flat and traditional tires. This table will help you consciously choose the right solution for your car.

Not every rim is suitable for Run Flats. The best options are rims with a protective flange and TPMS sensors – they detect pressure loss, as the driver may not feel the difference on stiffer tires.

PNCS - Pirelli Noise Cancelling System

PNCS (Pirelli Noise Cancelling System) is a technology used in Pirelli tires, featuring a special sound-absorbing foam inside the tire, significantly reducing cabin noise – by 2–3 decibels – improving ride comfort, especially in electric and premium cars.

Seal Inside / ContiSeal

Seal Inside is a self-sealing technology used by Pirelli, featuring a special sticky layer inside the tire that automatically seals punctures (e.g., from a nail), allowing you to continue driving without pressure loss and without having to stop immediately.

MultiGrip (or Dual Compound)

MultiGrip is a technology mainly used in sport tires, employing different rubber compounds within one tire – harder in the center for durability and softer on the shoulders for better cornering grip and dynamic driving.

NanoPro-Tech

NanoPro-Tech is a Bridgestone-developed rubber compound technology with nano-particles, reducing rolling resistance, improving fuel efficiency, and providing excellent grip – especially on wet surfaces.

Modern tire technologies are more than marketing slogans – they offer real solutions impacting comfort, safety, and vehicle performance. Whether you seek quieter rides, longer durability, better grip, or puncture resistance – it’s worth paying attention to applied technologies and choosing tires that fit your driving style and car type.

How to check tire age? – DOT

Tire age is very important – even if unused, tires may lose their properties after a few years. Production date information can be found in the DOT code, where the last four digits indicate the week and year.

Example:

• DOT XXXX XXXX 0413

– this means the tire was manufactured in the 4th week of 2013, i.e., late January or early February 2013.

If the tire shows only a three-digit code (e.g., 079) – it means the tire is from before the year 2000 and should definitely no longer be used.

How old can a safe tire be?

• It’s recommended to not use tires older than 6 years, even if they appear new and were stored well.
• 10 years from the production date is the absolute maximum – after this, the rubber hardens and loses its driving properties, even if the tread looks good.

Tire construction type – radial or diagonal?

Tires may feature a letter marking for internal construction type:

• R – radial tire. Currently the standard construction type, where carcass layers run radially from bead to bead. Provides greater comfort, better grip, and durability.
• D or no marking – diagonal (bias-ply) tire (now very rare). Mainly used in agricultural machinery or motocross.

Summary

Reading tire markings is a basic skill for every driver. It allows you to consciously choose the right tires for your car, driving style, and road conditions. Understanding symbols is not just a technical matter – it’s a guarantee of safety, comfort, and tire durability.

Don’t buy tires “by guess” – read, analyze, and choose wisely. It’s an investment not only in durability but most importantly in safety.