What is a retread?

Retreading is the generic term for tyre reconditioning which extends the useful life of a worn tyre for its original purpose by the addition of new material.

In the majority of cases the tread rubber is the only part of a tyre to wear away. The structure of the tyre remains intact. As the tyre construction has been produced to be capable of more than one life, to use this potential by replacing the worn tread makes sound environmental and economic sense. Whilst a car tyre is retreaded only once, commercial vehicle tyres are often retreaded two or three times and aircraft tyres many, many times.

To manufacture the average car retread takes 4.5 gallons less oil than the equivalent new tyre. With commercial vehicle tyres the savings are even greater, estimated to be in the region of 15 gallons per tyre.

The Manufacturing Process

After INITIAL INSPECTION of the worn casing to judge its acceptability for processing, the remaining unwanted old tread is removed. This process is called BUFFING and it provides a profile and surface texture in preparation for the application of a new tread.

SECONDARY INSPECTION then takes place during which time any necessary correction work is carried out prior to continuation of the process.

The application of a new tread and sometimes sidewall veneer is the next stage. This is called the BUILDING process. When the operator is satisfied that all criteria have been met the built tyre then moves on to the curing operation.

CURING or VULCANISATION can be carried out in different ways. Either in an individual curing matrix (known as a mould), or in an autoclave, a vessel which takes a quantity of tyres and is generally used for commercial vehicle tyres. During the curing process the physical properties of the tread change and the newly applied material forms a permanent chemical bond with the existing casing.

After curing, a FINAL INSPECTION is made to rule out any defect which would impair serviceability or the safety of the user. Unacceptable tyres are rejected and scrapped.

What are the Legal Requirements?

By law retreads have to be manufactured according to EC Regulations 108 (car tyres) or 109 (commercial vehicle tyres). To find out more about these, click here.

Source: Retread Manufacturers Association