A radial tire (more properly, a radial-ply tire) is a particular design of automotive tire (in British English, tyre). The design was originally developed by Michelin but, because of its advantages, has now become the standard design for essentially all automotive tires. A small variety of cars, the most popular kind of automobile. ... Firestone tire A tire (U.S. spelling) or tyre (UK spelling) is a roughly toroidal piece of (usually) rubber placed on a wheel to cushion it. ... British English is a term primarily used by people outside of the UK to refer to the form of the English language spoken in the British Isles. ... Michelin logo Michelin (full name: Manufacture Française des Pneumatiques Michelin, French manufacturer of tyres Michelin), based in Clermont-Ferrand, France in the Auvergne région of France, is primarily a tyre (In American English, tire) manufacturer but is also famous for its series of travel guides and road maps...

Tires are not fabricated just from rubber; they would be far too flexible and weak. Within the rubber are a series of plies of cord that acts as reinforcement. In the past, the alternating plies were laid within the tire at angles of +45 degrees and -45 degrees from the direction of travel so that they criss-crossed each other at 90 degrees. Because the plies were laid "on the bias", such tires were referred to as "bias ply tires". Look up Cord in Wiktionary, the free dictionary Cord has several meanings: String or Rope Cord Automobile Vibrating cord A measurement of the volume of firewood A power cord or extension cable In electronics, a cable Cord, a former American car marque founded by Errett Lobban Cord. ...

By comparison, radial tires lay all of the cord plies at 90 degrees to the direction of travel (that is, across the tire from lip to lip). This design avoids having the plies rub against each other as the tire flexes, reducing the rolling friction of the tire. This allows vehicles with radial tires to achieve better fuel economy than vehicles with bias-ply tires. It also accounts for the slightly "low on air" (bulging) look that radial tire sidewalls have, especially when compared to bias-ply tires. Fuel efficiency, sometimes also referred to as fuel economy and commonly gas mileage in the United States, is a numeric measure often used to describe the amount of fuel consumed with regard to the distance travelled in a transportation vehicle, such as an automobile. ...

As described, a radial tire would not be sufficiently strong and the surface in contact with the ground would not be sufficiently rigid. To add further strength, the entire tire is surrounded by additional belts that are oriented along the direction of travel. First made of tire cord, these belts were later made of steel (hence the term "steel-belted radial") and subsequently aramid fibers such as Kevlar. This outer belt also helps the tire resist punctures from road debris. Aramid fiber (1961) is a synthetic fiber, a fire-resistant polyamide, is a favorite for aerospace and military; bullet-proof protective armor fabric, as well as an asbestos substitute. ... Kevlar, also known as Twaron and poly-paraphenylene terephthalamide, is a synthetic fibre that is five times stronger than steel, weight for weight. ...