1. SCOPE
This regulation covers new pneumatic tyres designed primarily, but not only, for vehicles in categories L1, L2, L3 and L4. */
However, it does not apply to tyre types designed exclusively for the "off road" use, which are marked "NHS" (Not for Highway Service) and to tyre types designed exclusively for competitions.
Because of the design characteristics of moped and motor cycle tyres, and particularly those of the tread, a substantial number of different types of tyres of the same nominal dimensions are available on the market. It appears desirable, for reasons of safety, that vehicles should be designed in such a manner as to accept all the different types of tyres which are available to the customer.
2. DEFINITIONS
For the purpose of this Regulation,
2.1. "Type of pneumatic tyre" means a category of pneumatic tyres which do not differ in
such essential respects as:
2.1.1. The manufacturer;
2.1.2. Tyre size designation,
2.1.3. Category of use (normal: for normal highway service; special: for special applications
such as on- and off-the-road; snow; moped),
2.1.4. Structure (diagonal or bias-ply, bias belted, radial),
2.1.5. Speed category,
2.1.6. Load capacity index,
2.1.7. Tyre cross-section;
2.2. "Structure of a pneumatic tyre" means the technical characteristics of the tyre's carcass.
The following structures of a pneumatic tyre are distinguished in particular:
2.2.1. "Diagonal" or "bias ply" describes a pneumatic tyre structure in which the ply cords
extend to the beads and are laid at alternate angles substantially less than 90 degrees to the centre line of the tread, 2/
2.2.2. "Bias belted" describes a pneumatic tyre structure of diagonal (bias-ply) type in which
the carcass is restricted by a belt comprising two or more layers of substantially inextensible cord material laid at alternate angles close to those of the carcass,
2.2.3. "Radial" describes a pneumatic tyre structure in which the ply cords extend to the beads
and are laid substantially at 90 degrees to the centreline of the tread, the carcass being
*/ As defined in the Consolidated Resolution R.E.3 (document TRANS/WP.29/78/Rev. 1). 2/ Applicable also to Regulation No. 54.