CIO Tyres Pvt. Ltd.

Pre-cured retreading differs from mould cure retreading in that the tread is already vulcanised to shape with the tread pattern defined. As for conventional retreading preparation may be manual, semi-automated or computer controlled. The cemented casing which should be tacky is rim mounted and inflated to approx 1.5 bar. The cushion may be attached to the tread prior to building or applied directly to the prepared casing.

 

Uncured cushion rubber is applied between the two cured surfaces of the tread and casing and is cured (vulcanised) to bond tread and casing together. Cushion usually has a high natural rubber content providing good tack to enable the tread to be instantly attached to the casing ensuring maximum cured adhesion.

 

Other than endless tread bands where appropriate automation is provided for application, treads may be pre-cut to length before application. The tread should be cut to the same length, depending on pattern match, as the measured buffed circumference, which will allow for a slight tension during application and ensure that the shoulders will grip into the cushion. A tread, which is cut longer than the measured circumference, would result in air trapping. A tread, which is cut too short will increase the tension and could result in the splice opening. It is necessary to match the tread pattern.

 

If more than one join is required to allow for use of tread ends, the joints are not made too close to each other.

The tread ends should be cut perfectly square with the sides, and be perpendicular to the base. After cutting the tread ends are textured by buffing to remove all surface glaze. A sanding or finishing machine may have to be used to remove all surface glaze from the bonding side of the tread and provide a fine even, broken texture. Any areas not properly sanded must be treated separately by hand or the tread given a further pass through the machine. Excessive sanding results in reduction of undertread thickness.