Fast Ford - - How To Fit: Auto Specialists Focus Rs Intake -

In or­der to un­der­stand what makes a tyre do what it does, let’s go back to ba­sics and look at how one is ac­tu­ally put to­gether. Al­most all ra­dial road tyres are con­structed in more or less the same way, with the only ma­jor dif­fer­ences be­ing the ex­act com­pounds of rub­bers used and the fi­nal tread pat­tern de­sign.

The process of build­ing a tyre starts with the steel beads. Th­ese are then en­cap­su­lated in rub­ber and form the tyre bead as we know it, and pro­vides the start­ing point for the rest of the tyre to be built upon. The next step is the tyre liner, which is a non-por­ous ny­lon­re­in­forced rub­ber used to form the ba­sic shape of the tyre. This cre­ates an air­tight seal be­tween the steel beads so the tyres can be in­flated – hence need­ing to be made from a non-por­ous ma­te­rial to pre­vent mois­ture in the air es­cap­ing and de­flat­ing the tyre.

On top of the liner the tyre body plies are added. Th­ese are made from ny­lon-re­in­forced rub­ber and help give the tyre its shape. The num­ber of body plies de­pends on the ap­pli­ca­tion of the tyre, but a typ­i­cal road tyre will fea­ture two or three of th­ese ny­lon plies.

Next come the steel belts. Th­ese are steel re­in­forced sheets of rub­ber that are added to give the tyre strength and dura­bil­ity. The num­ber and type of steel belts used will help de­ter­mine the fin­ished tyre’s load and speed rat­ings. Again the num­ber of steel belts used de­pends on the ap­pli­ca­tion, but typ­i­cally you will find two or three lay­ers in most road tyres.

The blend of plies and steel belts is then capped of with a fi­nal layer of ny­lon-re­in­forced rub­ber, be­fore the tread cap is ap­plied. The tread cap is the fi­nal, thicker layer of rub­ber that even­tu­ally forms the tread pat­tern of fin­ished the tyre. The com­pounds of the rub­bers used in the tread cap will al­ter de­pend­ing on the in­tended pur­pose (ul­ti­mate grip race tyre or long-last­ing road tyre, for ex­am­ple) and man­u­fac­turer’s spec­i­fi­ca­tions.

At this stage the tyre is still ‘green’, and the lay­ers of soft, sticky, pli­able rub­ber need to be cured be­fore they can be used on the road. The cur­ing process in­volves ap­ply­ing both heat and pres­sure to the tyres in a spe­cific tyre cur­ing press. This causes all the lay­ers to bind to­gether to cre­ate what is ef­fec­tively a rub­ber lam­i­nate, and cures and har­dens the rub­ber to give the de­sired char­ac­ter­is­tics. The cur­ing press also in­dents the tread pat­tern de­sign into the outer tread cap layer, as well as all the re­quired side­wall mark­ings and tyre in­for­ma­tion.

There’s a lot more to a tyre than just the outer tread cap layer

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