ISO 13326:1998

This International Standard specifies test methods carried out under controlled conditions for verifying the uniformity of tyres for passenger cars, commercial vehicles and motorcycles.

NOTE — Lack of uniformity around a tyre produces variations in forces applied by the tyre to the vehicle and this influence is repeated with each revolution of the tyre. At the present state of the art, however, it is impossible to manufacture perfectly uniform tyres. A rigid control of the complete manufacturing process can only minimise the unavoidable imperfections of materials, components and processes affecting uniformity.

Methods for measuring the geometrical run-out of the tyre in both radial and lateral directions are covered, as well as methods for measuring the following parameters:

-radial force variation;

-lateral force variation;

-ply steer;

-conicity.

Not all of these measurements will necessarily be relevant in every situation.

This International Standard does not include methods for measuring the static and the dynamic unbalance nor methods related to tyre-wheel assemblies.

The test methods specified in this International Standard are not intended for the gradation of tyres or the definition of quality levels.