GB/T 26732-2025 Process for retreading of tyres
1 Scope
This document specifies the requirements for process for retreading pneumatic tires.
Note: It does not include plasticizing and mixing process of rubber used for retreading tires, and does not include the production process of pre-vulcanized tread, pre-vulcanized buffer rubber and other materials.
This document is applicable to the retreading of inflated car tires, truck tires and construction machinery tires, but does not applicable to the retreading of belted pneumatic tires and solid tires.
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 - Vocabulary
GB/T 7037 Retreaded tyre for truck
GB/T 14646 Retreaded tyre for passenger car
GB/T 21286 Repair of pneumatic tyres
GB/T 45291 Retreaded tyres for earth-movers
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
For the purposes of this document, the terms and definitions given in GB/T 6326 and the following apply.
3.1
mouldless vulcanized
no mould vulcanization of retreaded tire, after the molding of raw rubber tread, in the vulcanization tank
3.2
tread engraving
carve out pattern on the tread of a tire without pattern with a engraving machine
Note: There are two types of tread engraving: before vulcanization and after vulcanization.
3.3
mouldless vulcanized tread engraving retread
mouldless engraving retread
retread tires adopt the technology of mouldless vulcanized and tread engraving
Note: Mainly used for large construction machinery tire retreading.
4 Requirements for process for retreading of tyres
4.1 General
Process for retreading of tyres is classified into 3 types according to technical characteristics:
— Pre-vulcanized retreading, mainly applicable to the retreading of truck tires and small construction machinery tires. The schematic diagram of the process is shown in Annex A, Figure A.1;
— Mould retreading, mainly applicable to the retreading of car tires, truck tires and construction machinery tires. The schematic diagram of the process is shown in Figure A.2;
— Mouldless vulcanized tread engraving retread, mainly suitable for the retreading of large construction machinery tires. The schematic diagram of the process is shown in Figure A.3.
The main stages of the 3 types of retreading process include: tire selection, grinding, repair (optional), spraying glue (not suitable), molding, vulcanization and inspection.
The retreaded tire conveyor system shall prevent tire ground contamination after grinding and before vulcanization, and the tire suspension rails or carts can be used.
4.2 Pre-vulcanized retreading
4.2.1 Tire selection
4.2.1.1 Requirements
Select the tire body that meets the refurbishment requirements in accordance with GB/T 7037, GB/T 14646 and GB/T 45291.
4.2.1.2 Major equipment
The major equipment used in tire selection are as follows:
a) Necessary equipment: tire inspection machine, charging inspection machine (can be implemented in the charging grinding machine), electric pulse nail eye detection machine;
b) Recommended equipment: non-destructive testing equipment (including laser speckle inspection machine, X-ray inspection machine, etc.).
4.2.1.3 Procedures
The procedures of tire selection are as follows.
a) Tire body cleaning: remove visible stones, nails and other impurities.
b) Tire body dryness.
c) Manually inspect the inside and outside of each tire on the tire inspection machine by looking, tapping, listening and touching to find out the damage and mark it. The loose rubber layer at the damaged site shall be removed. If conditions permit, non-destructive testing equipment can be used to further examine the tire body.
d) Radial truck tires and car tires shall be charged with 150kPa to 200kPa air pressure for inspection.
e) The parts that affect grinding shall be treated.
f) Fill in the construction card according to the tire body inspection.
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 Requirements for process for retreading of tyres
Annex A (Informative) Flow chart of process for retreading production of tyres
