Tread shoulder

Tread shoulder Upper portion of the sidewall affects tread heat dissipation and tire cornering properties. 

Tire mold design initially begins with determination of the inflated dimensions of the required tire size. By use of inflated tire and growth characteristics of the tire, preliminary plyline and mold dimensions are computed (Figure 14.6). Once the mold boundary dimensions, location of the plyline, and tread width and depth are known, the contours of the tread, shoulder, sidewall, and bead components can be established. These dimensions and contours are developed using computer-aided engineering techniques (Figure 14.7). 

Overcuring is encountered to some degree in all compounds of any thickness because of the slow conductance of heat through mbber. Earthmover tires may have tire shoulder gauges in excess of 0.3 m (- 12 in.). The outside/inside are overcured to effect a satisfactory state-of-cure in the tread mbber. 

Mineral oils also known as extender oils comprise of a wide range of minimum 1000 different chemical components (Figure 32.6) and are used extensively for reduction of compound costs and improved processing behaviors.They are also used as plastisizers for improved low temperature properties and improved rubber elasticity. Basically they are a mixture of aromatic, naphthanic, paraffinic, and polycyclic aromatic (PCA) materials. Mostly, 75% of extender oils are used in the tread, subtread, and shoulder 10%-15% in the sidewall approximately 5% in the inner Uner and less than 10% in the remaining parts for a typical PCR tire. In total, one passanger tire can contain up to 700 g of oil. 

Peel Strength. Samples were prepared by cutting 2.5" (63.5 mm) wide radial sections, bead to bead. The sample was then sectioned into two 1.25" (31.75 mm) radial strips, which were each cut circumferentially at the centerline of the tread resulting in four test specimens (2-SS and 2-OSS). Each sample was cut with a razor knife for a length of 1" (25.4 mm) from the skim end of the test strip, midway between the belts, to facilitate gripping the ends in the T-2000 stress-strain tester jaws. The sides of each specimen were scored midway between the belts, to a depth of 1/8" (3.175 mm) radially from the end of the gripping surface to the end of belt 2 in the shoulder area, providing a 1" wide peel section. The peel test was performed at 2"/min (50.8 mm/min) at 24°C. 

Mostly, 75% of the extender oils are used in the tread, sub tread, and shoulder regions of a tire. About 10%-15% are used in the sidewall, 5% are used in the inner finer, and less than 10% are used in the remaining parts. A typical tire can contain up to 700 g of oil. All types of mineral oils should be handled and used with care, but special care is required in the handling of aromatic oils. High aromatic oils also referred to as distillate aromatic extracts (DAEs) or simply extracts have been traditionally used as extender oils for elastomeric applications [27]. Their popularity is explained by their good... 

A tyre retreading process in which new rubber is apphed as tread, on the tyre shoulders and on the tyre sidewalls. 

A large proportion of the circa 3.7 x 106 t/yr of natural mbber used in tires is consumed in tmck tires, off-the-road tires, and aircraft tires, all of which demand a low heat buildup performance. The retreading of tmck tires was also the province of natural mbber until the precured process was developed. Prior to the advent of this technique, the tack of natural mbber was essential for the unvulcanized mbber to adhere onto the buffed carcass, and the thickness of the shoulder region was such that the low heat buildup of natural mbber was essential to ensure that no failure occurred in service. With the precured tread process neither of these attributes were necessary and, synthetic mbber, which was and continues to be used, was found to give particularly good wear performance under low severity conditions, especially in the United States. However, work (56) has shown that natural mbber-based formulations can be developed which give a similar order of wear performance to the all-synthetic mbber tread, but with the additional benefit of lower rolling resistance, and hence better fuel economy. 

Shoulder belt wedge High-adhesive rubber compound in the shoulder region between the belts and casing improves tread wear and durability. 

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