GB/T 40716-2021Test method for the air retention of motor vehicle tyres (English PDF)

汽车轮胎气密性试验方法

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

October 11, 2021

Implementation date

May 1, 2022

Scope

GB/T 40716-2021 is the English-translated version of 汽车轮胎气密性试验方法.

China's national test method for the air retention of motor vehicle tyres. Every tyre loses pressure: rubber is permeable to air, and the inner liner that slows the loss is a compound chosen for exactly that property. The rate matters more than it appears to. An underinflated tyre wears at its shoulders, runs hot, consumes measurably more fuel, and handles worse, and the pressure loss is gradual enough that a driver who does not check will never notice it happening. Since surveys consistently find a large fraction of vehicles running below their specified pressure, the tyre's own retention is a real contributor to national fuel consumption and to tyre life. The test measures the loss rate under controlled temperature over a period long enough to distinguish real permeation from the settling of a newly mounted tyre, which is the measurement's main practical difficulty.

Document preview — GB/T 40716-2021

National Standard of the People's Republic of China

ICS: 83.160.10
Classification: G41

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

1 Scope ............................................................................................................
2 Normative references
3 Terms and definitions
4 Test equipment ..............................................................................................
5 Test conditions ..............................................................................................
6 Test procedure ..............................................................................................
6.1.4 After checking according to
6.2 Test steps
6.2.1 Put the two test tyres prepared in accordance with
7 Data processing ............................................................................................
8 Test report .....................................................................................................

Foreword

NATIONAL STANDARD OF THE PEOPLE'S REPUBLIC OF CHINA ICS

83.160.10 CCS G 41

Test method for air retention of motor vehicle tyres

Test method for air retention of motor vehicle tyres 1 Scope

This document specifies the test method for air retention of motor vehicle tyres under static conditions, including test equipment, test conditions, test procedure, data processing, and test report. This document is applicable to the air retention test of tubeless passenger car tyres and truck tyres.

2 Normative references

The contents of the following documents, through normative references in this text, constitute indispensable provisions of this document. Among them, for dated references, only the edition corresponding to that date applies to this document. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 2977 Size designation, dimensions, inflation pressure and load capacity for truck tyres

GB/T 2978 Size designation, dimensions, inflation pressure and load capacity for passenger car tyres

GB/T 6326 Tyre terms and definitions

HG/T 2177 Appearance quality of tyres

3 Terms and definitions

The terms and definitions defined in GB/T 6326 and the following ones apply to this document.

6.1.3 Connect the atmospheric pressure sensor and adapter to the valve stem. Check the tyre-rim assembly and the adapter (including the connection part with the sensor), to ensure that the accessories are not leaking.

6 Test procedure ..............................................................................................

6.1.4 After checking according to

6.1.2 and 6.1.3, park the tyre-rim assembly at the test temperature for 48 h (the temporarily-used spare tyre shall be parked for more than 48 h). If the inflation pressure drops more than 3 kPa during the period, follow

6.1.2 again. If necessary, reassemble the tyre and rim.

6.2.1 Put the two test tyres prepared in accordance with

6.1 in a temperature-controllable environment; adjust the atmospheric pressure to the test inflation pressure; start the test; and ensure free air circulation. During the test, the tyre shall not be moved to avoid pressure fluctuations.

6.2.2 Continue to check and record the inflation pressure, ambient temperature, and atmospheric pressure every day. If the revised slope value changes abnormally, check again for leaks.

6.2.3 After 14 days of the test, if the difference between the inflation pressures of the two test tyres does not exceed 6 kPa, the test continues. Otherwise, recheck according to

6.1.2 and restart the test.

6.2.4 Continue the test according to the standard until the end of the test period. During the test, continue to monitor and evaluate the data results.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 13 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 6326 · HG/T 2177

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