There are a number of tyre size systems in use in the modern automobile industry, they include: -

  • Alpha-Numeric Sizing System,

  • Metric Sizing System,

The Eurometric system is commonly used all over the world. A typical tyre size is written like this: 195/65 R15. Furthermore, if an Eurometric tyre has a “C” at the end, it means the product is designed for a commercial vehicle. So a 195/70 R15C tyre is, in essence, the same as a 195/70 R15, aside from its intended purpose.

  • ISO Metric Sizing System

  • Millimetric Sizing System

  • Light Truck Numeric System

  • P-Metric Sizing System,

  • Light Truck Metric Sizing System

Similar to the P-Metric system, except the P is replaced with the LT light truck designation. Also, LT-Metric and P-Metric tires differ in construction.

  • Light Truck High Flotation System

 

American p-metric tyre size system

The North American P-metric system, is the main alternative to marking tyre sizes. It was first introduced by American tyre manufacturers in 1977 and typically looks like this: P205/80 R14.

If the size begins with a “P”, it marks the tyre as fit for passenger cars, as well as minivans, SUVs and small pickup trucks. “LT”, on the other hand, signifies products for light trucks.

Exceptions

There are, however, still a few metric-system tyres with “full-profile.” Profiles of 80 and 82 typically omit the profile altogether, such as “165 R13” tyres. In this example, these would be equivalent to 165/80 R13 tyres.

Advantages of metric tyre size systems

  • Having all the information as provided by metric size systems makes buying replacement tyres a lot easier through cross-reference.