Abstract: A sinker unit for preparing an annular unvulcanized tread band comprises an annular mold for supporting the tread band and an expandable annular sinker member for forcing the tread band against the inner surface of the mold. The sinker member includes side walls which are resiliently biassed outwardly so that the sinker member is maintained in a tensioned condition when it is forced against the tread band. The sinker member may be forced against the tread band by means of an expanding air bag underneath the sinker member.

Abstract: A method of treading or re-treading tires involves compression of the wearing surface of the tread. A tread strip, which may be an annular band, is compressed in a direction parallel to its longitudinal axis and is bonded to a tire carcass, while being maintained under compression. This may be done by compressing a tread band into an undersized mould; apparatus for assisting this is also described. Alternatively, the tread strip may be of finite length, for example to form a lug, in which case the strip is formed with a radius of curvature less that of the surface to which it is to be applied, so that the convex (wearing) surface of the strip is compressed upon application to the carcass.