Tire Size Codes and Age Checks Guide Drivers

Guides for buying and maintaining car tires explain the standard size notation, such as 205/55 R16, where the first number is the width in millimetres, the second is the side‑wall height percentage, R denotes radial construction and the final figure is the rim diameter in inches. The designation also includes a load index (e.g., 91, indicating a maximum load of about 615 kg) and a speed rating (e.g., H for 210 km/h). Winter suitability is marked by M+S or the Alpine‑symbol 3PMSF, the latter requiring a certified snow‑grip test. Tread patterns vary, with V‑shaped designs enhancing water evacuation and asymmetric patterns improving corner stability.

The DOT code on a tire’s sidewall shows its production week and year; for example, 3520 means the 35th week of 2020. Although a tire may be brand‑new to the buyer, it can be several years old, which reduces grip and lengthens braking distances, especially in wet conditions. Experts advise inspecting tires after six years and replacing them around ten years, regardless of tread depth, to maintain safety. Major manufacturers such as Michelin, Continental and Bridgestone stress regular age checks as part of vehicle safety inspections.