GB/T 29042-2020 Thresholds and grading of rolling resistance for motor vehicle tyres
1 Scope
This standard specifies the terms and definitions, rolling resistance coefficient threshold and grading requirements as well as test methods for thresholds and grading of rolling resistance for motor vehicle tyres.
This standard is applicable to new radial tyres for passenger cars, ultra light and light trucks as well as trucks and buses, but excluding tyres with nominal rim diameter ≤10 inches or with nominal rim diameter ≥25 inches, T-type temporary-use spare tyres, special ST metric tyres for highway trailers, floatation radial tyres for light trucks, truck and bus tyres with speed capacity less than 80km/h (excluding), racing tyres, studded tyres and professional off-road tyres.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 6326 Tyre terms and definitions
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 29040 Test methods of rolling resistance for motor vehicle tyres - Single point test and correlation of measurement results
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 6326 and GB/T 29040 and the following apply.
3.1
professional off-road tyre
tyre mainly designed to be used in harsh off-road conditions. For passenger car tyres and ultra light and light truck tyres with single tyre load index not greater than 121 and speed symbol of N or above, the groove depth shall not be less than 11mm, the pattern unsaturation shall not be less than 35%, and the speed symbol shall be Q and below; for ultra light and light truck tyres with single tyre load index not greater than 121 and speed symbol of M or below, or ultra light and light truck tyres or truck and bus tyres with single tyre load index of greater than 121, the groove depth shall not be less than 16mm, the pattern unsaturation shall not be less than 35%, and the speed symbol shall be K or below
4 Rolling resistance coefficient threshold and grading requirements
4.1 Rolling resistance coefficient threshold and grading requirements
The rolling resistance coefficients of passenger car tyres, ultra light and light truck tyres as well as truck and bus tyres shall not be greater than those specified in Table 1.
Table 1 Rolling resistance coefficient thresholds for passenger car tyres, ultra light and light truck tyres as well as truck and bus tyres
Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Rolling resistance coefficient threshold and grading requirements 5 Test methods Annex A (Normative) Establishment of reference laboratory for rolling resistance test of tyres
