Modern tyres provide comfortable cushioning compared with the old iron wheels. But the thing which makes movement more comfortable is not just the rubber material of the tyres but also the air they enclose. This pressurised air volume is also the reason why tyres are able to carry their load. Modern passenger car tyres are constructed with textile cords arranged radially to the direction of travel, hence the name radial tyres. These so-called body plies are arranged in one or two layers and held together by several coatings of rubber. The radial tyre gives considerably better comfort than the old-fashioned cross-ply tyre, which has completely disappeared from the passenger car market.
The soft carcass is stiffened by numerous belts lying diagonally and transversely to the body plies and which create stability in the tyre construction. These belts may be in steel (steel radial tyres) and/or textile material, e.g. polyester, rayon, nylon, Kevlar, etc.
The tread rubber consists of a combination of synthetic and natural rubber, depending on the properties required. Together with the tread pattern, the rubber ensures a safe grip on the road in all situations.
The tread pattern is designed to give good water drainage and directional stability (longitudinal grooves), but also good driving and braking capacity (transverse grooves). Many modern tyres have far less rolling resistance than former models, as a result of special silica-based rubber mixtures and different belt structures
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