The international tire marking and rating convention is governed by the ETRTO (European Tire and Rim Technical Organization) and the TRA (Tire and Rim Association)in the United States. These tire ratings are internationally accepted and applied. The designed tire speed rating system forms part of this rating system.
The tire’s sidewall will indicate the speed rating of a tire. A tire speed rating- H defines a maximum speed of 130 mph at which the tire must still perform as designed. A V-rated car requires a tire designed to operate to a maximum of 149 mph and can thus not be fitted with an H-rated tire.
The speed rating system was developed to control the safe speeds at which tires must still perform as per the intended design. An alphabetic letter is assigned to assign the speed rating from A to Z corresponding to 3 mph (5km/h) to 186 mph (330 km/h).
These tire speed ratings are used by the vehicle manufacturers to define what the maximum speed is that the vehicle has been designed to achieve and what the corresponding tire speed rating must be. It is possible to fit an H-rated tire to a car that requires V-rated tires, but the result may be both illegal and unsafe. Let’s look at the impact of not sticking to the defined speed ratings when fitting tires.
Tire Speed Ratings: Safety and Legal Perspectives
Institutions involved in the financing and insurance of vehicles or the enforcement of road safety regulations need the vehicle manufacturers to define the safe operating conditions for each model to be homologated for the county of sale. The application of tire speed ratings is rigorously enforced.
If you have an accident with your car and the insurance assessor finds that your vehicle is not fitted with the correct speed-rated tire, your claim will be denied. Insurers have to cover the risk that they underwrite by ensuring that your vehicle is well maintained and the condition of your tires and tire speed rating is correct. Don’t give them a reason to turn down your insurance claim.
Traffic officials will also check that the tires fitted to your car are of the correct speed rating and have more than 3/32 of an inch tread-depth left. If this is not the case your vehicle may be impounded and you will be fined. You will also have to take your vehicle in for inspection after having the correct tires fitted. The defined tire speed ratings are there for very good reason, your safety and the safety of fellow road users.
You are allowed to fit tires with a higher speed rating to a vehicle requiring tires of a lower speed rating. For example, you will be able to fit V-rated tires to a vehicle requiring H-rated tires. The vehicle requires tires to safely operate up to a maximum speed of 130 mph (H-rated tires), thus by fitting tires that can safely operate to a maximum of 149 mph (V-rated tires), you comply with the law and road regulations.
Where Do I Find The Tire Speed Rating On A Tire
All tire manufacturers comply with the ETRTO convention for tire sidewall designations. On the sidewall of a tire the following information must be displayed:
Tire Width in mm
Tire Aspect Ratio (Height of the sidewall / Width of the tire)
Construction Type: R – Radial, B – Bias
Rim Size in inches
Load Index – how much mass each tire can carry
Speed Rating – the maximum design speed of the tire
If the sidewall marking is: 205 / 55R / 16 91V, the speed rating is the very last symbol, V.
The tire is 205 mm wide, has an aspect ratio of 55 (205mm x 55/100 = 112.75mm sidewall height), and has a Radial construction. The rim size is 16 inches and the load rating of 91 means that the tire can bear a mass of 1356 lbs. (615 kg) and a speed rating of V which indicates a safe maximum speed of 149 mph (240 km/h).
Other markings on the sidewall of the tire will indicate features such as SSR (Self-Supporting Run-Flat tire) a vehicle manufacturer’s designation (A – Audi, M – Mercedes Benz, etc.) whether the tire is suitable for Mud and Snow conditions, the DOT mark indicating approval for use by the Department of Transport and the week and year of manufacture.
Tire markings can be very confusing to those not accustomed to working with them often. They are very important and you should check the owner’s manual in your vehicle for an accurate description of what you must fit in your vehicle.
Conclusion:
Tire speed ratings are defined by the vehicle manufacturers when they homologate a new model for a market. The homologation process entails the definition of all the operating criteria for which the vehicle has been designed, tested, and approved.
Deviating from the defined speed rating for a vehicle is not advised as this may affect the safe operation of the vehicle and the state of roadworthiness of the vehicle. Vehicles involved in accidents are routinely checked by insurance assessors for compliance with the defined speed rating and condition of tires at the time of the accident.
It is permitted to fit a tire with a higher speed rating to a vehicle requiring a lower speed rating, but not vice versa. Always check with your tire fitment expert that you’re the tires fitted are in full compliance with the recommended speed rating for your vehicle.
What Are All The Speed Ratings?
| Speed Rating | Speed (km/h) | Speed (mph) | Speed Rating | Speed (km/h) | Speed (mph) | |
| A1 | 5 | 3 | L | 120 | 75 | |
| A2 | 10 | 6 | M | 130 | 81 | |
| A3 | 15 | 9 | N | 140 | 87 | |
| A4 | 20 | 12 | P | 150 | 94 | |
| A5 | 25 | 16 | Q | 160 | 100 | |
| A6 | 30 | 19 | R | 170 | 106 | |
| A8 | 40 | 25 | S | 180 | 112 | |
| B | 50 | 31 | T | 190 | 118 | |
| C | 60 | 37 | U | 200 | 124 | |
| D | 65 | 40 | H | 210 | 130 | |
| E | 70 | 43 | V | 240 | 149 | |
| F | 80 | 50 | W | 270 | 168 | |
| G | 90 | 56 | Y | 300 | 186 | |
| J | 100 | 62 | XR | 300+ | 186+ | |
| K | 110 | 68 |
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