Truck for tires up to 24,5"

The retreading of truck tyres can be performed with two different systems, the cold and the hot method.

The initial phases up to the building process are common to both methods.

The inspection of the casings can be done in different ways: visually by means of a normal inspection spreader, with pressure test and also with a shearography machine. Some retreaders combine these different inspection methods in order to have higher data allowing to judge if the casing can be retreaded or has to be scrapped.

Afterwards, in the buffing process the residual tread is removed from the casings and then, according to the type of method used, the options are whether to grind/brush the sidewalls (hot method), or to leave the original brand of the casing if the tyre will be retreaded with cold method.

After buffing the process foresees the casings preparation, with the activities of skiving, repairing, filling and cementing, all aimed at having the casing ready for the building process. Normally the tyres are moved from one working station to the other by means of a monorail, because the buffed tyre should not touch the ground to avoid contamination of its buffed surface.

After the above mentioned common phases, the process changes according to the method used:

• with the cold method, first there is the application of the cushion gum and then of the precured tread strip. Afterwards inner and outer envelopes are mounted on the tire and the vulcanization process is done in autoclaves, which are heated electrically or by steam;
• with the hot method the procedure is similar to passenger tyres, the building of tread and sidewalls is done by cold feed extruders, and then the tires are cured in presses with the selected mold according to the patterns desired.