What Goes Into Making A Modern Tire?
Modern tires contain a lot of technology, but for the most part people never appreciate just what goes into a tire or how it does its job. For most people, they never think about their tires, rarely checking them for the correct tire pressure and taking them for granted. It is only when there is a failure in the tires, or an incident occurs which makes us think about them, that we really ever appreciate just what a big job modern tires do.
The initial step in making a modern tire is to prepare the raw materials. Raw materials include natural and synthetic rubber, sulfur, carbon, steel and a range of other materials and chemicals. It is typical for tire making rubber batches to be made weighing in excess of 1,100 pounds, which takes place in large machines which resemble cement mixers.
The tire compound batch is then heated to soften the material and ensure the chemical components are thoroughly well-mixed. The batch is then returned to the mixing machines where further “ingredients” are added to the batch and a further mixing process is carried out. Different batches are made with different formulations depending on the use to which they will be put: sidewall, main tire face and beading are all made using different “recipes” to provide different characteristics which will be needed in the final tire.
The body, beads and tread are then created. Each applicable rubber batch is turned into sheets of thick rubberized fabric known as “ply” which is then used to produce a layered component for the tire body. There may be as many as four plies in a typical car tire, which help provide structural strength and redundancy if there is a failure when in use.
The beads are created by a wire wrapping machine which forms wire lengths into rings which are then coated in rubber. The sidewalls and treads are created using an extruder; a machine which provides for the batch compound to be further treated and mixed, then heated until it is forced into a “die” – the die forces the rubber compound into the desired shape. Sidewalls are created by being coated with a plastic sheathing and then rolled under intense pressure. Tire treads are created by the compound rubber being cut into strips and stored in metal casings called “books”.
A skilled assembler then puts all the various components together on a steel drum. The plies are laid around the drum, with the ends glued to one another and further plies are added to form a cross-sectional arrangement which is then trimmed to size. The treads and sidewalls are also added and once fully assembled the finished article is known as a “green tire” which is removed from the steel drum for curing.
Curing takes place in a “clam” or mold, which contains a bladder. The green tire is placed in the mold and the bladder fitted in the center of the tire. Once closed, the bladder is inflated forcing the outer parts of the tire into contact with the inside contours of the mold and heated steam is applied to cure and form the tire’s final shape.
Finally, the tire is placed through a quality control process which checks for flaws and voids within the tire fabric. Most tires pass this inspection process due to the high quality standards of the technology and manufacturing processes involved. The finished tire is then shipped to distribution centers for onward shipping to customers until it finally arrives on your vehicle.
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