How Are Tires Made?
April 9th, 2015
It’s pretty easy to just take tires for granted, but did you ever think about how they’re made?
Even though much of the tire-building process is now automated, tire companies still depend a lot on skilled factory workers to complete tasks. Here’s a simplified version of how a tire is made:
- Modern rubber formulations for tires include natural latex rubber, synthetic rubber polymers derived from crude oil, sulfur, silica, oils and chemicals and carbon black. Carbon black is the fine, sooty powder left over when crude oil or natural gas are burned with insufficient oxygen. It’s a crucial ingredient in tire formulations that helps disperse heat and stabilize the other components of the tire. These ingredients are mixed and heated in enormous hoppers, and the batches are checked regularly by industrial chemists to ensure consistency.
- Batched and mixed rubber is driven through mills, where rolling cylinders squeeze the material into thick sheets, which are then used to build specific parts of the tire. The inner plies of the tire, for instance, are rubberized fabric that are layered on top of each other. The tire’s bead is a wire bundle which is formed into a ring on a wire-wrapping machine and covered with rubber. The material for the tread goes from the batch mixer to an extruder and is formed into sheets, then sliced into strips and stored in flat metal cases called “books.” Sidewall rubber is rolled after being covered with a protective layer of plastic.
- At a tire-building machine, the racks of beads, books of tread rubber and rolls of sidewall rubber are delivered to a technician. The technician wraps the rubberized plies around a collapsible drum, holding the plies together with glue. Next, the beads are added, with additional plies which are then shaped with power tools. The tread layers and sidewalls are glued into place, and the “green tire” is removed from the machine.
- From there, the green tire is placed inside a clamshell-style mold. Inside the mold, a bladder inflates with steam, forcing the tread rubber against the interior of the mold and forming the tread pattern. The steam heats up the tire to 280 degrees; the time spent in the mold depends on the design of the tire.
- Once the tire is built, formed and cured, the quality control process begins. Each tire is examined for defects like bubbles or voids; it’s inflated and spun on a test wheel, with sensors monitoring the tire for trueness and roundness. Hundreds of tires from each production run are used for destructive testing, sliced open to check for internal air pockets, run against metal drums to test endurance or pressed onto metal studs to determine resistance to punctures. Random tires are X-rayed to look for internal flaws.
Tire makers are also mindful of field information such as warranty claims and feedback from consumers and tire dealers, and take that into account for product design and QC. At St. Lucie Battery & Tire in West Palm Beach, FL, we hope this little look behind the scenes of tire manufacturing was interesting to you! Schedule an appointment for tires and auto repair in West Palm Beach, FL with St. Lucie Battery & Tire.
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Posted in: Tires 101