Tire speed index – what is it and how to adjust it?

The tire speed index is one of the most important parameters every driver should know. It determines the maximum speed at which a tire can be safely operated when fully loaded. An incorrectly selected speed can lead to accelerated tire wear, reduced traction, and even dangerous driving situations.

In this article, we'll explain exactly what a speed rating is, how to read it from tire markings, and what it means for different types of vehicles—from passenger cars to SUV and vans. You'll also learn how to properly fit seasonal tires and the risks of choosing a model with the wrong speed rating. We'll also provide practical tips and a table for quickly comparing speed ratings.

Contents:

• Tyre speed rating definition – what does the letter on the sidewall mean?
• Speed index in motorcycle and car tires – similarities and differences
• Speed index and seasonal tires – summer, winter and all-season
• Consequences of choosing the wrong tire speed index - safety and regulations
• Tire speed index table
• Frequently asked questions about tire speed ratings

Tyre speed rating definition – what does the letter on the sidewall mean?

The speed rating is a letter symbol that indicates the highest speed (expressed in km/h) at which a tyre can operate without risk of damage when properly inflated and loaded according to its specifications.

• Where can I find the index number?

  The speed rating is located on the sidewall of the tire , next to the load index . For example, in the 91V marking:

  • 91 – indicates the load index (maximum tire load).
  • V – is the speed index (in this case max. 240 km/h).

• Why is it important? Exceeding the speed specified by the manufacturer can lead to excessive tire heating, reduced grip, and in extreme cases, delamination or cracking of the tread.

Reading markings – how to interpret the speed rating symbol?

Each letter assigned to the speed rating corresponds to a specific value expressed in km/h. The further the letter in the alphabet, the higher the maximum speed for that tire.

• Examples of popular speed ratings:
  • T – up to 190 km/h (often with winter tires).
  • H – up to 210 km/h (popular in compact cars).
  • V – up to 240 km/h (middle and upper class cars).
  • W – up to 270 km/h (sports cars).
  • Y – up to 300 km/h (high-class cars, e.g. sports coupes).


• Letter symbol and unit "km/h":

  It's worth emphasizing that the speed rating symbol is always a letter, and the km/h unit indicates the maximum speed in kilometers per hour. Phrases like "what does km mean" or "what does km mean" stem from a misunderstanding of tire markings.

• Speed index and load capacity:

  The speed index always appears together with the load index (e.g. 94W), so when choosing tires you need to pay attention to both parameters at the same time.

When selecting tires with the appropriate speed rating, it's also worth remembering the importance of rims. Rim diameter and width affect the tire's profile and, therefore, its stability at higher speeds. Changing rim sizes, especially to larger aluminum rims , often requires tires with a higher speed rating to maintain safety and vehicle homologation compliance.

Speed index in motorcycle and car tires – similarities and differences

Speed ratings are a key parameter not only for car tires but also for motorcycle tires. Although the letter markings appear similar, their meaning and interpretation may differ slightly depending on the type of vehicle. Choosing the correct rating for a motorcycle is particularly important, as it determines the stability and safety of the bike.

Specifics of speed ratings for motorcycle tires

• Are the markings the same as on cars?

  Yes, in most cases, motorcycle tires also use a letter speed rating system (e.g., H, V, W). These indicate the maximum speed at which the tire can be operated under full load.

However, in the case of motorcycles, there are also additional letter-number markings or specific symbols that refer to the tire construction (e.g. "Z" for tires designed for very high speeds above 240 km/h).

• Why is precise index matching so important?

  In motorcycles, choosing a tire with the appropriate speed index is even more important than in cars, because it affects:

  • cornering grip
  • stability when driving at high speeds
  • resistance to tread heating during dynamic driving

Using tires with a lower than recommended speed rating on your motorcycle can lead to instability and even loss of control of the vehicle.

Speed index and seasonal tires – summer, winter and all-season

Speed rating is a parameter that should be considered when choosing any type of tire – regardless of whether they are summer, winter, or all-season models. In this section, we explain how to choose seasonal tires based on speed rating, what markings are typical for each type of tire, and what regulations govern their use.

Speed index for summer tires - requirements and typical markings

When it comes to summer tires, the speed rating must be no lower than the vehicle manufacturer's recommendation. Choosing a tire with a higher rating is acceptable, but it doesn't provide any tangible benefits in everyday use – the tires are stiffer, which can reduce driving comfort.

• Typical high indexes in summer tires:
  • H (up to 210 km/h) – often found in compact cars.
  • V (up to 240 km/h) – used in mid-range and high-end cars.
  • W (up to 270 km/h) and Y (up to 300 km/h) – intended for high-performance vehicles.
• Example markings:
  • 91V – tire designed for a speed of 240 km/h and a maximum load of 615 kg.
  • 94W – a tire approved for speeds up to 270 km/h and a load capacity of 670 kg.

Speed index for winter tires – specifics and permissible deviations

In winter, regulations allow for greater flexibility in selecting a speed rating. Winter tires can have a speed rating lower than the vehicle manufacturer's recommendation, but not lower than Q (160 km/h). This solution stems from the fact that drivers are less likely to reach high speeds during the winter season.

• Obligation to mark the restriction:

  If a tire has a speed rating lower than the factory-recommended rating, the driver must place a sticker in a visible place – usually on the dashboard – informing about the maximum permissible speed for the tire.

All-season tires and speed ratings – compromise solutions

All-season tires are a compromise between summer and winter tires – also in terms of speed rating.

• Why compromise?

  Manufacturers strive to select tire compounds and construction to ensure the highest possible top speed in summer and adequate traction in winter conditions. In practice, this means that all-season tires typically have intermediate ratings—typical are T (190 km/h) or H (210 km/h).

• All-season tires with higher indices (e.g. V or W) are less common and are most often intended for mid-range and high-end cars that mainly drive on city roads.

Consequences of choosing the wrong tire speed index - safety and regulations

Choosing tires with the appropriate speed rating is not only a matter of compliance with the vehicle manufacturer's recommendations, but above all, safety. An incorrect rating can lead to serious road hazards and entail legal consequences and insurance issues.

Risks related to speed rating mismatch – road safety

Using tires with a speed rating lower than required can pose a real threat to the driver, passengers and other road users.

• Tyre overheating : At speeds higher than the speed rating allows, the tyre may overheat, leading to deformation and increasing the risk of the tread cracking or tearing.
• Deterioration of driving characteristics : Too low a speed index affects the stability of the vehicle – the following may occur:
• extended braking distance
• instability in corners
• poorer handling on wet surfaces
• Wrong speed rating and failures : Under load (e.g. full trunk, towing a trailer) the risk of tire damage increases even more.

Legal and insurance consequences of using unsuitable tires

Selecting non-compliant tires may also result in administrative sanctions and problems in the event of vehicle damage.

• Fine and confiscation of vehicle registration certificate : During a road check, the police may impose a fine for tires with an inappropriate speed index and confiscate the vehicle's registration certificate until the tires are replaced.
• Compensation problems : The insurer has the right to refuse to pay compensation under the third-party liability or comprehensive insurance policy if it proves that the use of tires with a speed index lower than the recommended one contributed to the occurrence or consequences of the accident.
• Technical inspection : The diagnostician may not allow the vehicle to be driven during a periodic technical inspection if he finds that the tyres do not comply with the vehicle type approval.

When are deviations from the speed rating permitted?

However, there are situations in which the use of tires with a lower speed rating than recommended by the vehicle manufacturer is legally permissible. This applies primarily to winter tires. In this case, regulations permit the use of tires with a lower speed rating, as long as it is not less than Q, which corresponds to a maximum speed of 160 km/h. However, this requires a sticker clearly displayed in the vehicle indicating the maximum speed limit for the tires.

Tire speed index table

When choosing tires for your vehicle, it's important to know how to properly read the markings on their sidewalls. Among the most important is the speed rating, which appears as a letter and indicates the maximum speed at which a given tire can operate under full load. To help you navigate the maze of symbols, we've prepared a comprehensive table that allows you to quickly check what the individual speed rating letters mean.

Complete tire speed index chart – A to Y (and more)

The table below provides a complete list of letter designations used in tire speed ratings, along with their corresponding maximum speeds expressed in kilometers per hour (km/h). This practical tool will help every driver ensure that the selected tires meet the vehicle manufacturer's requirements and legal requirements.

Interpreting the data in the table is simple: if the tire sidewall is marked "91V," the letter "V" indicates that the tire's maximum speed is 240 km/h. Please note that selecting a tire with a lower speed rating than recommended by the vehicle manufacturer may be illegal and unsafe in everyday use.

Special speed ratings (ZR, VR, W) – what do they mean?

Tire markings also feature special speed ratings, which are used for exceptionally high-performance vehicles. The ZR symbol indicates tires designed for speeds above 240 km/h. This symbol was used in older markings and is often accompanied by a letter indicating a more specific speed range, such as ZR(Y). Similarly, the VR symbol indicates that the tire is rated for speeds above 210 km/h. VR and ZR are less commonly used today, having been replaced by more precise designations such as W (up to 270 km/h) and Y (up to 300 km/h). Tires with these symbols are primarily intended for sports and luxury cars that travel at high speeds on highways.

How to choose the right speed rating for your vehicle?

Selecting the correct speed rating should always be based on the vehicle manufacturer's recommendations. Information about the required rating can be found in several places: in the vehicle's owner's manual , on the nameplate , usually located on the door pillar or sill, and on the fuel filler flap . Remember that for summer and all-season tires, you should use tires with a speed rating equal to or higher than the factory-designated rating. The exception to this is winter tires, where the installation of tires with a lower rating is permitted, but this requires the vehicle to be marked with the maximum speed rating for such tires.

Frequently asked questions about tire speed ratings