The tyres are crucial functional elements for the transmission of longitudinal, lateral and vertical forces between the vehicle and road. The tyre properties should be as constant as possible and hence predictable by the driver. As well as their static and dynamic force transmission properties, the tyre requirements described below – depending on the intended use of the vehicle – are also to be satisfied.
As tyres significantly affect the handling properties of vehicles, the properties of original tyres – the tyres with which the vehicle is supplied to the customer –are specified by the vehicle manufacturers in conjunction with the tyre manufacturers. However, spare tyres usually differ from the original tyres, despite their similar designation; hence handling characteristics can change. Individual vehicle manufacturers have therefore decided to identify tyres produced in accordance with their specifications by means of a symbol on the sidewall of the tyre or to sell tyres which meet the specifications of original tyres at their manufacturing
branches.
All tyres and rims are standardized to guarantee interchangeability, i.e. to guarantee the possibility of using tyres from different manufacturers but with the same designation on one vehicle and to restrict the variety of tyre types worldwide.
Within Europe, standardization is carried out by the European Tyre and Rim Technical Organization or ETRTO, which specifies the following tyre requirements :
- tyre and rim dimensions;
- the code for tyre type and size;
- the load index and speed symbol.
Passenger car tyres are governed by UNO regulation ECE-R 30, commercial vehicles by R 54, spare wheels by R 64, and type approval of tyres on the vehicle by EC directive 92/23/EC.
In the USA the Department of Transportation is responsible for the safety standards.
The Tire and Rim Association, or TRA for short, is responsible for standardization.
In Australia, binding information is published by the Federal Office of Road Safety, Australian Motor Vehicle Certification Board
InGermany, theDINStandards(Deutsches Institut fu¨r Normung) and the WdK Guidelines (Wirtschaftsverband der Deutschen Kautschukindustrie Postfach 900360,
D-60443, Frankfurt am Main) are responsible for specifying tyre data. All bodies recognize the publications of these two organizations.
At the international level, the International Organization for Standardization (ISO) also works in the field of tyre standardization and ISO Standards are translated into many languages.