Method of vulcanizing a prevulcanized tread

A method for retreading a tire carcass having an arcuate tread engaging crown with a prevulcanized annular tread having a pattern of ribs and grooves on its exterior road enaging surface and a substantially flat interior cross sectional configuration when in the unstressed state;

• said method comprising:
• (a) applying the tread to the crown of the carcass with an unvulcanized bonding rubber intermediate layer therebetween, the tread being elastically deformed to conform to the carcass crown, the application of the tread to the carcass being effected in such a manner that the occlusion of air between the tread and the carcass is avoided;
• (b) securing a stressing belt annularly around the assembled tread and carcass, said stressing belt being an elongated endless band extending annularly around the road engaging surface of the assembled tread with its longitudinal direction running in the same direction as the tread and its width corresponding at least to that of the tread, the belt having openings to allow a surrounding fluid to pass therethrough to at least some of the road engaging surface of the tread so that the pressure of the fluid is transmitted to all of the ribs and grooves of the tread, said belt further being elastic, secured annularly around the tire and pressed thereagainst by shrinkage in its longitudinal direction under the influence of heat and moisture thereby providing around the longitudinal direction of the tread a uniform, radially inwardly directed stress to hold the elastically deformed tread on the carcass, said belt further being capable of withstanding elevated temperatures and pressures sufficient to vulcanize said bonding rubber intermediate layer;
• (c) vulcanizing the intermediate layer of bonding rubber by subjecting the tread and carcass assembly with the fluid-permeable, shrinkable and elastic stressing belt therearound to the action of heat and pressure in an enclosed chamber whereby as the adhesive power of the intermediate layer of bonding rubber decreases during heating prior to vulcanization, the tread is held securely in position and distortion of the carcass or of the bonding rubber layer is avoided.