There are two methods that can be used for tire retreading: hot retreading and cold retreading. Only carefully selected and properly inspected casings are used in either of these methods. The manufacturing process itself is also identical for both methods, up to the point of applying the tread material and performing the vulcanization.
During hot retreading, the process of applying the tread material is virtually identical to the production of a new tire.
The tread material is taken directly from the extruder and applied to the buffed casing. Afterwards the tread/casing assembly is cured in a vulcanization mold with the required tread pattern. The pattern on the tread is formed during the vulcanization process just as it is when a new tire is made.
Hot retreaded truck tires from Continental are retreaded from bead to bead. The main advantage of this principle is that the sidewalls are renewed, ensuring that the quality of the hot retreaded tire is comparable with that of a new tire.
Using the cold retreading method, a patterned and prevulcanized tread is applied to the buffed casing. This tread is placed, under constant tension, together with an unvulcanized bonding ply onto the buffed casing; pretensioning ensures already prior to vulcanization that the tread adapts optimally to the tire contour and guarantees that the parts are effectively bonded together while the tire is in the autoclave (curing chamber). Then the prepared tire is “packed” into a curing tube (envelope) and cured under pressure in the autoclave.
ECE Regulation No. 109 defines type approval standards in the production of retreaded pneumatic tires for commercial vehicles and their trailers. This regulation defines strict quality control measures that have been compulsory for retreaders since September 2006 to ensure high-quality retreaded tires.