BLENDING

Raw materials including pigments, chemicals, and up to 30 different kinds of rubber are mixed in giant blenders called Banbury machines, which operate under tremendous heat and pressure. They blend the many ingredients together into a black, gummy compound that will be milled again and again.

MILLING

The cooled rubber is processed into slabs that are transported to breakdown mills. These mills prepare the different compounds for the feed mills, where they are slit into strips to become sidewalls, treads or other parts of the tyre. Still another kind of rubber coats the fabric that will be used to make up the tyre's body. Many kinds of fabrics are used: polyester, rayon or nylon.

BEAD

Another component, shaped like a hoop, is called the bead. It will fit against the vehicle's wheel rim.

PLY

Next come two layers of ply fabric, the cords. Next, a pair of chafer strips is added, so called because they resist chafing from the wheel rim when mounted on a car.

TREAD

Now the tyre builder adds the steel belts that resist punctures and hold the tread firmly against the road. The tread is the last part to go on the tyre. After automatic rollers press all the parts firmly together, the tyre, now called a green tyre, is ready for curing and inspection.

CURING

The curing press gives the tyres their final shape and tread pattern. Hot moulds shape and vulcanize the tyre. The moulds contain the tread pattern, the sidewall markings of the manufacturer and those required by law. Tyres are cured at over 300 degrees for 12 to 25 minutes, depending on their size.

INSPECTION

If anything is wrong with the tyre – even the slightest blemish! – it is rejected. Some flaws are caught by an inspector's trained eyes and hands; others are found by specialized machines. Inspection doesn't stop at the surface. Some tyres are pulled from the production line and X-rayed to detect any hidden weaknesses or internal failures. In addition, quality control engineers regularly cut apart randomly chosen tyres and study every detail of their construction that affects performance, ride or safety.