tire glossary

How to read tire specifications?
A typical example: 205/55 R16 91V

• 205: The width of the tire in millimeters (from sidewall to sidewall).

• 55: The ratio of sidewall height to width as a percentage. Here, the sidewall height is 55% of the width (205 mm).

• R: The tire construction type, here Radial (nowadays standard).

• 16: The inner diameter of the tire in inches, matching the rim size.

• 91: The load index (LI) indicates the maximum weight the tire can carry (here 615 kg).

• V: The speed index indicates the maximum speed the tire is rated for (here 240 km/h).

Why are summer and winter tires different?
Summer and winter tires differ in their rubber compounds, tread patterns, and performance at different temperatures:

• Rubber Compound

  • Summer tires: Harder rubber, remains stable at high temperatures for optimal grip and reduced wear.

  • Winter tires: Softer rubber, stays flexible in cold weather to ensure better traction.

• Tread Pattern

  • Summer tires: Flat treads with fewer sipes, for good grip on dry and wet roads and to minimize aquaplaning.

  • Winter tires: Deeper treads and many sipes to better channel snow and water, providing better grip on snow.

• Performance

  • Summer tires: Optimized for temperatures above 7°C.

  • Winter tires: Designed for temperatures below 7°C, offering better grip on snow, ice, and cold roads.

Switching between summer and winter tires is crucial for year-round safety and efficiency.

How to identify the age of a tire?
The DOT number (Department of Transportation) on the sidewall indicates the tire's production date and location. The last four digits are critical:

• Example: DOT XXXXXX 0125

  • 01: Production week (1st week, i.e., January).

  • 25: Production year (2025).

  • This tire was produced in the 1st calendar week of 2025.

Tire Age Recommendations

• Maximum age: Replace tires after 6 to 8 years, even if the tread is still sufficient. The rubber ages, reducing grip.

• Regular checks: Inspect tires older than 5 years annually for cracks, brittleness, and general damage.

• Storage: Proper storage (dry, cool, and dark) helps preserve tire properties.