Taking note of the recommended tires for your vehicle will help you make sure you are purchasing the suitable tires and verify that your car is already equipped with the appropriate tires. Using tires that aren’t compatible with your car might shorten their lifespan and even change how your speedometer reads.
If you look at the sidewall of your tire, you will notice numerous alphanumeric codes and symbols. What do those tire markings mean?
Tire width
The tire width appears as the first set of numbers following the tire’s brand name. Measured from side to side, the breadth includes the tire’s sidewall but does not include any raised branding or rim protectors. For the vast majority of car tires, the number “5” always comes at the end of the tire width measurement, which is expressed in millimeters (mm). Tire width is significant since it might impact your car’s fuel efficiency and performance. Your tire’s rolling resistance and grip are affected by the amount of rubber that comes into contact with the road. While a larger contact patch increases grip, it also increases rolling resistance, which reduces fuel efficiency.
Aspect ratio
The aspect ratio is represented by the first two figures that follow the width. This figure represents an estimate of the tire’s sidewall height. It is frequently referred to as the profile of the tire. Higher profile sidewalls (more than 50%) offer more flex to cushion you over bumps and potholes, whereas low profile tires (profile less than 50%) require the sidewall to be stiffer. As a result, tires with a higher profile typically offer greater comfort. Because the firmer sidewall prevents the tire from moving around as much during cornering, lower profile tires typically offer superior handling.
Rim Diameter
The diameter of the metal wheel that sits in the center of a tire is called the rim diameter, and it is usually expressed in whole inches. High-performance vehicles are better off with larger tires and wheels because of their less noticeable curvature, which increases the contact patch and grip. Now, though, these wheels are installed more for show than functionality. In cars from the 1960s or earlier, the letter preceding the number denotes the type of construction used in the tire casing, such as radial construction (‘R’), bias-ply (‘B’), or diagonal construction (‘D’).
Load index
This is the highest weight in kilos that the tire is capable of supporting. The maximum weight that your tire can safely support is indicated by its load index, which may be found using the “tire load index table” below. This relatively new method of determining a tire’s weight capacity was developed to provide tire comparisons greater consistency.
It’s risky to put more weight on your tires than they can support. It may cause the vehicle to become unsteady and result in a blowout tire failure.
Passenger automobile tires typically have a load index ranging from 75 to 104, with each index number denoting a certain load weight that the tire can safely support.
Speed index
The final letter denotes the fastest speed at which your tire can sustain the maximum weight specified by its load index for a maximum of ten minutes. Every car has a minimum speed index that the manufacturer mandates. Driving faster above the safe limit of a tire’s design can be hazardous, just as carrying too much weight. At higher speeds, the tire will not handle well, and the extra weight may force it to fail. This could result in a major collision at motorway speeds.
It is safe, legal, and appropriate to install a tire with a greater speed index than the one that was originally installed, but not one with a lower index. Additionally, it can render your insurance void.
Other markings
Brand name, tire name or pattern name, country of manufacture, manufacturing date code, European ECE Type Approval. Others are:
TWI – Tire Wear Indicator. It is a sign that your tire needs to be changed if you can see this marking clearly.
SSR – This sidewall symbol indicates tires that are “Self-Supporting Run-flat,” meaning that their strengthened walls allow them to continue to function even if pressure is lost.
MOE – This marking denotes another run-flat tire, but for Mercedes-Benz drivers (Mercedes Original Equipment tire).
M+S – This marking marks a tire that is ideal for mud and snow conditions.
