Abstract: A method and apparatus for manufacturing a tire in which the sidewalls overlap the ends of the tread band. The method comprises the steps of inserting an extensible tubular releasing element around the carcass plies at each end of an assembly drum, wrapping the sidewalls on these elements, applying another tubular element on the sidewalls, and overturning the tubular elements to spread apart the sidewalls in an open position aside of the assembly drum. The carcass, in the form of a first-step cylindrical sleeve comprising open sidewalls, is transferable to a (second-step) forming drum to be torically formed against a separately prepared assembly comprising the belt pack and the tread band. Next, the band ends are turned down onto the toric carcass and the sidewalls are folded back against the carcass and over the ends of the tread band.

Abstract: A tire is described which has a tread pattern provided with a large central channel (2) interposed between two continuous circumferential ribs (8), and a pair of large circumferential grooves (4) located at symmetrically opposite positions relative to the central channel (2). Also provided are transverse grooves (3) having a symmetrically converging inclined extension, the axial inclination of which increasingly grows larger towards the central channel (2). The longitudinal grooves (4) each consist of a sequence of oblique portions (4a) giving the grooves a broken-line course, so that each land portion or block (5, 6) delimited by the grooves (3, 4) has a corner (5a, 6a) projecting inwardly of the corresponding circumferential groove (4) with respect to the opposite corner (5b, 6b) of the circumferentially adjacent block.

Abstract: A high-transverse-curvature tire (1), in particular to be mounted on the front wheel of a motor-vehicle, comprises a belt structure (6) including, in a radially external layer (9a), a plurality of circumferential coils (7a), axially arranged side by side, of a cord (7) wound at a substantially zero angle with respect to the equatorial plane (X--X) of the tire. The area occupied by rubber blocks (10) formed in a portion of the tread band (8) having a length equal to the pitch (p) of the tread pattern and a width equal to the axial development of the tread band (8), is between 70% and 90% of the total area of said portion.

Abstract: A process for the manufacture of tire for high speed two-wheeled vehicles comprising making a cylindrical sleeve, attaching annular bead wires to the axial ends of said sleeve and shaping the sleeve into a toroidal configuration. A belt structure made of coils of cords is applied to the crown of said toroidal configuration. The belt is reinforced with HE cords which can be deformed to enable the tire carcass to be so largely expanded into the mold to achieve completely molding of a tread band.

Abstract: A wire, generally made of steel and used to make composite elements of elastomeric material, is submitted to an electrodeposition process in an electrolytic bath for being coated with a zinc/cobalt alloy in which the average cobalt content is lower than 1%. In the coating thickness made of the zinc/cobalt alloy, different cobalt concentrations exist, that is a 1% to 3% concentration at the area close to the metal wire and a concentration as low as 0.5% maximum at the overlying area. Adhesion promoters for example consisting of cobalt neodecanate, added to the elastomeric material, promote the adhesion of said elastomeric material to the wire.

Abstract: A tire (1) having sidewalls (3) with an annular strip (8) within which a plurality of ribs (9) is formed. The ribs are disposed in mutual side by side relation and circumferentially distributed. The annular strip (8) is made in the form of a hollow on a sidewall (3) of the tire (1) and is designed to display informative inscriptions (12) the characters of which (13) are defined by projections (19) projecting from the surface of the annular strip.

Abstract: A cord comprising at least a first pair and a second pair of wires (2a, 2b) of different diameter randomly disposed in transverse cross section thereof, is obtained by arranging in a nacelle (7) of a double-twisting laying machine, a twister (16) operating upstream of a preformer (15). The twister (16), rotating in a direction opposite to that of the impeller (5) and at a speed which is twice that of the impeller, neutralizes the internal torsional stresses induced in the wires (2a, 2b) by effect of the double twisting carried out upon the action of the impeller itself. Thus, a better control of the preforming operation executed on the wires (2a, 2b) disposed parallel in respectively coplanar axes is enabled.

Abstract: A tread pattern for motor vehicle winter tires having transverse grooves symmetrically converging toward an equatorial plane "X" of the tire. A pair of circumferential grooves (3) respectively defined by oblique stretches (3a) have an orientation converging toward the equatorial plane "X", in a direction opposite to the rolling direction "D" according to which the transverse grooves (2) converge. Grip hollows (6) of increasing width in a direction opposite to the rolling direction, are formed astride of each transverse groove (2), at two contiguous center blocks (4). A central separation cut (7) between the center blocks (4) defines therein separation walls (7a) arranged to come into mutual contact when in the ground contacting area.

Abstract: A vulcanizable rubber composition is described comprising a cross-linkable unsaturated chain polymer base including natural rubber, at least a copolymer obtainable by polymerizing a conjugated diolefin with a vinyl aromatic hydrocarbon, and a main carbon black-based reinforcing filler, wherein:a) the copolymer is obtainable by polymerizing in 1,2 form with the vinyl aromatic hydrocarbon at least 50% by weight of the conjugated diolefin, so as to obtain in the copolymer a quantity of from 30% to 70% by weight to the total weight of the same of an olefin fraction having a 1,2 structure, andb) the carbon black has a DBP absorption value measured according to ISO 4656-1 equal to at least 110 ml/100 g, a reduction in the DBP absorption value measured after compression according to ISO 6894 equal to at least 25 ml/100 g and a surface area measured by means of CTAB absorption according to ISO 6810 not greater than 120 m.sup.2 /g.

Abstract: In a tire for motor-vehicles, an auxiliary support element (9) is interposed between a carcass ply (3) and a belt structure (6). The support element is employed during the manufacturing step of the belt structure (6) in order to stably retain, on the sectors of a comb drum (10), coils (7a) consecutively formed by winding of an inextensible cord (7) therearound. The auxiliary support element (9) is made in the form of an elastomeric sheet containing short aramid fibers in an amount included between 1 and 10 parts by weight per 100 parts of elastomeric material, to increase the stretchability of said element without impairing its adhesiveness. The introduction of the short aramid fibers in the blend enables the thickness of the auxiliary support element (9) to be reduced to about 0.075 mm.

Abstract: A pair of high-transverse-curvature tires for two-wheeled vehicles is provided, in which the belt structure of the rear tire comprises a layer of inextensible cords disposed at a substantially zero angle with respect to the equatorial plane of the tire, preferably wound on a sheet of elastomeric material reinforced with aramid pulp, whereas the belt structure of the front tire comprises at least one radially outer layer of inextensible cords disposed at a substantially zero angle with respect to the equatorial plane of the tire and distributed with an axially variable density, and preferably another reinforcing layer at a radially underlying position. The zero-degree cords preferably are metallic cords of the high-elongation type, made of high-carbon steel.

Abstract: A tread for motor-vehicle tires has a raised pattern formed of a plurality of shaped blocks 7 distributed in circumferential rows 3, 4, 5, 6 disposed in parallel and in side by side relation. The number of the shaped blocks 7 arranged in each row gradually increases while moving from the equatorial plane X--X to the axial outer side edges 1a of the tread 1. Thus a gradual increase in the longitudinal stiffness of the shaped blocks 7 is achieved on passing from the side edges 1a of the tread 1 to the equatorial plane X--X, which brings about a reduction in the mobility of said blocks on the road contact patch and lower rolling noise.

Abstract: In a vulcanization mold (2) for vehicle tires the rubber blend deposits are cleaned off by the action of one or more laser beams (9) supplied in the form of short-duration and high-energy pulses, which beams cause separation of the rubber blend by effect of the shock wave generated by them and hitting the operating surfaces of the mold (2). Each laser beam (9) is guided by a scanning unit (21a, 21b) mounted on a rotating column (16) for distributing the beam action over the whole circumferential extension of the mold.

Abstract: In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 1100 and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tires with low rolling resistance.

Abstract: A tire for motor vehicles includes a belt structure (3) which has consecutively overlapped first and second belt strips (5, 6) and a pair of side straps (7) overlying the second belt strip (6) adjacent to the side edges (6a) of the second belt strip. Each side strip (7) is made up of at least one cord circumferentially wound in a plurality of coils to form two radially superposed layers of coils disposed in axial side by side relation. The first belt strip (5), located adjacent to the carcass structure (2), substantially has the same width as the tread band (4), and laterally projects from the second belt strip (6) radially overlapped therewith. The second belt strip (6) has side flaps (6b) projecting from the side straps (7) and spaced apart from the first belt strip (5) by a spacing which progressively grows with distance away from the outer edges (7a) of the side straps themselves.

Abstract: A front tire for-wheeled vehicles comprising a carcass of toric form having a high transverse curvature and provided with a central crown and two sidewalls terminating in a pair of beads for anchoring to a corresponding mounting rim, a tread band located on the crown and a circumferentially-inextensible belt structure disposed between the carcass and tread band. The belt structure at a radially external position is comprised of a layer of cord coils substantially disposed at a zero angle to the equatorial plane of the tire in axial side-by-side relationship and extended from one axial extremity of the belt to the other axial extremity of the belt. The winding thickness of the cord coils increasingly grows from the equatorial plane to the belt axial extremities.

Abstract: A tire for a vehicle, that is representable by a dynamic rigid-ring tire model with concentrated parameters, has construction features that are substantially equivalent to concentrated parameters that fall within the following intervals corresponding to preselected indices of comfort:rb=100-300 (Ns/m)rbt=2-40 (Nms/rad)rcz=100-350 (Ns/m)rct=10-90 (Nms/rad)Ckx=18,000-70,000 (N),where rb is a radial foundation dampening of said dynamic tire model; rbt is a torsional foundation dampening of said dynamic tire model; rcz is a residual radial dampening of said dynamic tire model; rct is a residual torsional dampening of said dynamic tire model; and Ckx is a slipping stiffness of a brush model of said tread.

Abstract: A method of control to determine the comfort level of a tire of a wheel for a vehicle is based on a dynamic tire model with a rigid ring having concentrated parameters that represent construction characteristics of the tire. Some concentrated parameters are measured, others are determined by parametric identification through a test of passing over an obstacle of the tire. From testing eight curves of natural frequencies and dampenings are obtained that are compared with as many calculated curves obtained from the model. By checking the coincidence between the eight calculated curves and the eight experimental curves, the values of the other concentrated parameters are determined that cause the calculated frequencies and dampenings to coincide with the experimental ones.

Abstract: In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 110.degree. and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tires with low rolling resistance.