Tire speed rating (speed symbol) and load index are very important factors that determine tire performance. The common name for the load index and speed symbol is "service description".
The tire load index and speed rating for light truck tires have some specificity compared to the passenger car tires.
The term "Light Truck" covers great variety of vehicles, such as vans, SUV's and light duty pickup trucks. This is one of the reasons why the tires are labeled in many ways. It is also important to know what sizing system is applied in a tire designation.
There are several sizing systems for the light truck tire designations currently in use:
Before we begin to discuss about the tire sidewall informations it's important to know standard which was used for designation.
1 - MAX. LOAD SINGLE 1549 kg (3415 lbs) AT 550kPa (80 psi) MAX. PRESS. COLD
2 - MAX. LOAD DUAL 1399 kg (3085 lbs) AT 550kPa (80 psi) MAX. PRESS. COLD
What is a light truck?
A light truck is a United States federal classification for trucks or truck-based vehicles with a payload capacity of under 4,000 pounds (1,815 kg). Light truck class includes:
- Vans - most mini vans and full sized vans.
- SUV's – Mini SUV's, Compact SUV's, Mid size SUV's, Full size SUV's, Extended length SUV's.
- Light duty pickup trucks.
In other countries words usage and meanings are quite different.
Two types of the tyre size designation can be found on a tyre sidewall, a tyre width expressed in mm and the tyre width expressed in inches.
1. The tyre width expressed in mm
All tyres for the commercial vehicles must be marked with a
Service Description located after the size designation (European regulation ECE-R54). The service description consists of
load index and
speed rating (e.g. 156/150 L).
Listed below are a few examples of the truck/bus tyre size designations.
Here is an example of the tyre size designation for commonly used truck tyre: