“Mysterious Symbols”: What Do the Letters and Numbers on Car Tires Mean?

The mysterious letters and numbers on the sidewall of a car tire carry important information. What do they mean? Let’s explain!

When selecting car tires, drivers in the USA should primarily focus on the parameters set by the manufacturer of their vehicle. Any deviation from the specifications listed in the vehicle’s manual is not permissible—not only according to the vehicle’s instructions but also by law.

Therefore, when choosing tires, it is essential to pay attention to the necessary parameters—either by relying on store specialists who will find the appropriate tires or by doing it yourself. In this case, all the necessary information is already inscribed on the tire itself.

Typically, tire markings on the sidewall look like this:

205/55R16 91H (XL), where:

• 205: The first number indicates the tire’s width in millimeters (in this case, 205 mm).
• 55: The second number represents the aspect ratio, the height of the tire’s profile as a percentage of the width (in this case, 55% of 205 mm).
• R: The letter denotes the type of tire construction (R stands for radial).
• 16: The number indicates the nominal diameter of the wheel rim that the tire is designed to fit (16 inches).
• 91: The number represents the load index, the maximum load that the tire can support (in this case, 1356 lbs per tire).
• H: The letter indicates the speed rating, the maximum speed the tire can handle (in this case, 130 mph).
• XL: This designation indicates an extra load rating, meaning the tire has reinforced construction for higher load capacity.

Additional markings that may be found on tires include:

• M+S: Indicates all-season tires.
• Treadwear: Indicates the tire’s wear index—the higher the number, the more durable the tire.
• Tubeless: Indicates that the tire has a tubeless construction.
• Max Pressure: Indicates the maximum inflation pressure.
• Outside/Inside: Marks the outer and inner sides for tires with an asymmetric tread pattern.
• Rotation: Indicates the direction of rotation for tires with a directional tread pattern.

Example Tire Marking: 205/55R16 91H (XL)

1. Width: The tire width is 205 millimeters.
2. Aspect Ratio: The height of the sidewall is 55% of the tire’s width.
3. Construction: The tire has a radial construction (R).
4. Diameter: The tire fits a 16-inch rim.
5. Load Index: Each tire can support a load of up to 1356 lbs.
6. Speed Rating: The maximum speed the tire can handle is 130 mph.
7. Extra Load (XL): The tire has reinforced construction for higher load capacity.

With all this information, combined with the specifications from your vehicle’s manual, you can easily select the necessary tires from any tire brand that produces suitable rubber for your car.