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This standard is drafted in accordance with the rules given in the GB/T 1.1-2009.
This part replaces GB/T 7377-2008 Series of Cycle Tyres in whole. The following technical deviations have been made with respect to the GB/T 7377-2008 (the previous edition):
— modification of the cross-sectional drawings for the various types of tire parts to be more complete, and moved the classification of tread configurations from the original Annex C to Clause 4 “Classification” (see Clause 4; C.1.3 of Edition 2008);
— addition of the off-road crotchet type (CT) tyres (see 5.2);
— addition of the 5 new size designations for straight side and crotchet type tyres, and 3 original size designations are changed to the parameters table of new off-road crotchet type tyres (see Tables 1 and 2; Table 1 of Edition 2008);
— addition of the calculation of dimensions for off-road crotchet type tyres (see C.2);
— addition of the calculation of tire load (see Annex D);
— deletion of the size designations in the comparison table of straight side and crotchet type rims and old marking which have no corresponding size designations in the parameters table of each tyre (see Annex D of Edition 2008).
— modification of the content of the original Clause 9: “general tyres for hooked bead (HB) and straight side (SS) rims” is changed to 5.5; deletion of the markings should be specified as “tires with the best driving direction” and “tubeless” in GB/T 1702 Cycle Tyres, and the clause name is changed to “Tyres of size designations other than those specified in this standard” (see Clause 9 and 5.5; Clause 9 of Edition 2008).
This standard has been redrafted and modified adoption of International Standard ISO 5775-1:2014 Bicycle Tyres and Rims — Part 1: Tyre Designations and Dimensions.
This standard is changed largely from ISO 5775-1:2014 in structure; a list of the clauses in this standard and the equivalent clauses in the International Standard ISO 5775-1:2014 is given in the Annex A.
Technical deviations have been made in this standard with respect to ISO 5775-1:2014, and marked with perpendicular single line (|) at the margin of relevant clauses; A complete list of technical deviations, together with their justifications, is given in Annex B.
For the purposes of this standard, the following editorial changes have also been made:
— modification of the standard name of ISO 5775-1:2014.
This standard was proposed by China Petroleum and Chemical Industry Federation.
This standard is under the jurisdiction of SAC/TC 19 (National Technical Committee 19 on Tyres and Rims of Standardization Administration of China).
The previous editions of the standards replaced by this standard are as follows:
— GB 7377-1987, GB/T 7377-1997, GB/T 7377-2008.
Series of Cycle Tyres
1 Scope
This standard specifies the terms and definitions, classification, designations and markings, basic parameters, main dimensions and measurement methods of cycle tires.
This standard is applicable to the pneumatic tires for bicycle, tricycle and wheelbarrow.
This standard is not applicable to tubular sew-up tyres and non-pneumatic 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 (GB/T 6326-2014, ISO 4223-1:2002, NEQ)
GB/T 8170 Rules of Rounding of for Numerical Values & Expression and Judgement of Limiting Values
GB/T 23657 Series of Cycle Rims (GB/T 23657-2009, ISO 5775-2:1996, MOD)
HG/T 2906 Static Loaded Performance Testing Method for Cycle Tyres
3 Terms and Definitions
For the purposes of this document, the terms and definitions given in GB/T 6326 apply.
4 Classification
4.1 Tread structure
Cycle tires are classified into four types according to the structure of bead and rim: straight side (SS) tires [see Figure 1a)]; hooked bead (HB) tires [see Figure 1b)]; beaded edge (BE) tyres [see Figure 1c)]; crotchet type (CT) tires [see Figure 1d)].
a) Section of straight side (SS) tires b) Section of hooked bead (HB) tires
c) Section of beaded edge (BE) tyres d) Section of crotchet type (CT) tires
Keys:
1 — tread;
2 — section width (S);
3 — maximum overall width (W);
4 — crown thickness;
5 — section height (H);
6 — side wall;
7 — maximum overall diameter (D0);
8 — specified rim diameter (D);
9 — bead base;
10 — rim;
11 — measuring rim width (Rm);
12 — bead;
13 — side wall engraving or decorative pattern;
14 — apex.
Figure 1 Typical section of tyres
4.2 Tread configurations
Figure 2 shows the following two principal tread configurations which apply to bicycle tyres:
Tread type A corresponds to highway service tyres.
Tread type D corresponds to tyres for on-and-off road service tyres (e.g. mountain bikes).
Tread type A Tread type D
Figure 2 Tread configurations
5 Size Designations, Basic Parameters and Main Dimensions
5.1 Straight side (SS) and crotchet type (CT) tyres
5.1.1 Size designations of dtraight side and crotchet type tyres
The designations of straight side and crotchet type tyres shall be indicated as follows:
a) the nominal tyre section width (SN), in millimetres (mm);
b) the tyre construction code, which shall be a separated dash (—);
c) the nominal rim diameter, in millimetres (mm).
Example: straight side tire with nominal section width 37, mounted on the rim with nominal rim diameter 590 shall be designated as: 37-590
Foreword II
1 Scope
2 Normative References
3 Terms and Definitions
4 Classification
4.1 Tread structure
4.2 Tread configurations
5 Size Designations, Basic Parameters and Main Dimensions
5.1 Straight side (SS) and crotchet type (CT) tyres
5.2 Off-road crotchet type (CT) tyres
5.3 Hooked bead (HB) tires
5.4 Beaded edge (BE) tyres
5.5 Tyres than can be mounted on both hooked bead (HB) and straight side (SS) rims
6 Maximum and Minimum Dimensions of Design Tyres
6.1 Maximum section width (Smax) and minimum section width (Smin) of design tyres
7 Correction Value of Section Width of Design Tyre Mounted on Allowed Rim
8 Tyre Dimension Measurement Method
9 Tyres of Size Designations Other Than Those Specified in This Standard
Annex A (Informative) Structural Changes of This Standard with Respect to ISO 5775-1:
Annex B (Informative) Technical Deviations Between this Standard and the International Standard ISO 5775-1:2014 and Their Justifications
Annex C (Normative) Calculation of Tyre Dimensions
Annex D (Informative) Calculation of Tire Load
Annex E (Normative) Comparison Table of Size Designation and Old Markings Between Straight Side and Crotchet Type Tires
