Test method of measuring peripheral dimensions for tyres
1 Scope
This document describes the test method of measuring peripheral dimensions for pneumatic tires (outer tubes, inner tubes and cushion belts), including measuring tools and their accuracy requirements, measuring conditions, measuring methods, data calculation and processing, and test reports.
It is applicable to passenger car tyres, truck tyres, agricultural tyres, earth-mover tyres, industrial vehicle pneumatic tyres, motorcycle tyres, electric bicycle tyres and rickshaw 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 (including any amendments) applies.
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 2979 Size designation，dimensions，inflation pressure and load capacity for agricultural tyres
GB/T 2980 Size designation, dimensions, inflation pressure and load capacity for earth-mover tyres
GB/T 2982 Designation, dimensions, inflation pressure and load capacity of pneumatic tyres for industrial vehicles
GB 2983 Series of motorcycle tyres
GB/T 6326 Tyre terms and definitions
GB/T 7377 Series of cycle tyres
GB/T 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
GB/T 31548 Series of electric bicycle tyres
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 6326 apply.
4 Measuring tools and their precision requirements
4.1 Tyre barometer:
- ±5kPa, the measured air pressure is 500kPa or below;
- ±10kPa, the measured air pressure is above 500kPa.
4.2 Steel ruler and metallic tape (without radian): ± 1mm.
4.3 Vernier caliper: ±0.1mm
4.4 Groove depth gauge: ±0.02mm
4.5 Thickness gauge:±0.1mm
4.6 Calipers
4.7 Non-contact measuring instruments (such as laser measuring instrument): ±0.02mm
5 Measuring conditions
5.1 Tyres shall be kept still at room temperature for at least 24 h after vulcanization. Before inflation, it shall be kept still at 18℃ - 36℃ for at least 3h. If necessary, the to-be-measured parts on the tyre surface shall be cleaned, and the mould air vents or flashes at mould junctions shall be trimmed.
5.2 Tubeless tyre shall be installed on the measuring rim of tyre without inner tube, and inflated according to 5.3. In order to make the tyre bead contact with the rim in place, the inflation pressure can be appropriately increased on the premise of safety, and then adjusted to the specified pressure after the tyre bead contacts with the rim in place. The tyre with inner tube (including outer tube and inner tube, and cushion belt if necessary) shall be installed on the rim for measuring the tyre with inner tube and inflated according to 5.3.
5.3 Inflate the tyre to the inflation pressure specified in Table 1.
Table 1 Inflation pressure for measurement
Foreword
1 Scope
2 normative reference documents
3 terms and definitions
4 Measuring tools and their accuracy requirements
5 Measuring conditions
6 Measurement method
7 Data calculation and processing
8 test report
