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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the China Petroleum and Chemical Industry Association.
This standard is under the jurisdiction of National Technical Committee on Tyres and Rims of Standardization Administration of China (SAC/TC 19).
Drafting organizations of this standard: Triangle Tyre Co., Ltd., Shandong Linglong Tire Co., Ltd., Giti Radial Tire (Anhui) Co., Ltd., Sailun Group Co., Ltd., Beijing Research & Design Institute of Rubber Industry, Double Coin Tyre Group Ltd., Double Star Group Co., Ltd., zc rubber Group Co., Ltd., Guangzhou Vanlead Group Co,. Ltd., AEOLUS Tyre Co., Ltd., Sichuan Haida Rubber Group Co., Ltd., Qingdao Sentury Tire Co., Ltd., Zhejiang Cotan Tyre Co., Ltd., Michelin (China) Investment Co., Ltd., Continental Tires (China) Co., Ltd., Bridgestone (China) Investment Co., Ltd., Dalian Goodyear Tyre Co., Ltd., Shantou Haoda Tyre Test Equipment Co., Ltd., Heilongjiang Red Valley Automotive Test Co., Ltd., Shanghai General Motors Wuling (SGMW), Guangdong Matelong Automobile Technology Co., Ltd.
Chief drafters of this standard: Deng Shitao, Li Wu, Chen Shaomei, Zhang Weiguo, Xiao Shenglong, Wang Kexian, Xu Lihong, Mou Shouyong, Yu Ziping, Zhang Jinsheng, Wu Meidan, Huang Junqi, Yan Weiguo, Luo Jiangang, Li Zhongdong, Li Weisheng, Lu Yi, Ma Zhong, Fu Guangping, Yin Qingye, Chen Xun, Zhao Xinhong, Jia Yonghui, Qiu Yuqiang.
Test method for snow grip performance of passenger car tyres
1 Scope
This standard specifies the method for measuring the snow grip performance of passenger car tyres. To reduce the measurement deviation, this standard adopts the test method of comparing with standard reference test tyre.
It is applicable to the passenger car tyres.
2 Normative references
The following referenced documents are indispensable for the application 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
3 Terms and definitions
For the purpose of this standard, the terms and definitions established in GB/T 6326 as well as the following ones apply.
3.1
candidate tyre
tyre that is evaluated by testing
3.2
standard reference test tyre; SRTT
a set of special candidate tyres that are used as a benchmark in an evaluation system These tyres usually have carefully controlled design features to minimize variation and they are produced, controlled and stored according to the relevant standards.
3.3
control tyre
tyre which is used to indirectly obtain the comparison result between candidate tyre and standard reference test tyre by comparing with the candidate tyre and then the standard reference test tyre when the candidate tyre and the standard reference test tyre cannot be directly compared on the same vehicle
3.4
braking test
specified amount of anti-blocking brake system (ABS) braking carried out repeatedly on the same tyre in a short time
3.5
mean fully developed deceleration; mfdd
mean deceleration calculated according to the measuring distance recorded when the vehicle slows down between two specified speeds
3.6
snow grip index; SG
ratio of the snow grip performance between the candidate tyre and the standard reference test tyre
4 Test methods
4.1 Principle
The snow grip performance of passenger car tyres is tested by the deceleration method.
This test method is to test the deceleration performance of the tyre of a test vehicle equipped with ABS (anti-blocking brake system) during the braking process with an instrument. The test vehicle runs along a straight line at the initial speed during the test, and then its emergency braking is used, leading to the ABS action of the four wheels and the stable deceleration. The average deceleration of the vehicle from 25km/h to 10km/h is then calculated.
4.2 Test conditions
4.2.1 Road conditions
4.2.1.1 The snow road surface for testing is flat and even with the length above 500m, width above 5m and slope no greater than 2%.
4.2.1.2 The snow-piled road shall have a layer of at least 3cm-thick hard and compacted snow as the bottom layer and an about 2cm-thick compacted snow on the surface.
4.2.1.3 As for the snow compression index, ten measuring points shall be selected uniformly on the whole test road to calculate their average, and the maximum value does not differ from the minimum value by 8. The average of the snow compression index measured with snow hardness tester (CTI, see Annex A) is between 75 and 85.
4.2.2 Climate conditions
Ambient temperature measured at about 1m above the ground is between -21℃ and -7℃;
The snow temperature measured at about 1cm deep of the snow-piled road shall be between -21℃ and -9℃;
The temperature variation in the test process shall not exceed 10℃.
Direct sunlight or greatly changed sunlight or humidity shall be avoided during the test and the wind speed should not exceed 5m/s.
4.2.3 Test vehicle conditions
4.2.3.1 The test vehicle equipped with ABS system and applicable to both the candidate tyre and the standard reference test tyre are selected.
4.2.3.2 The test vehicle shall be equipped with a calibrated sensor for winter measurements, and the speed and distance data acquisition system shall be capable of storing the measurement results. The accuracy of the sensor and the system shall be such that the relative uncertainty of the measured or calculated mean fully developed deceleration is less than 1%.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Test methods
5 Test report
Annex A (Normative) Snow hardness tester
