A radial tire (more properly, a radial-ply tire) is a particular design of vehicular
tire
A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineering), t ...
. In this design, the cord
plies are arranged at 90 degrees to the direction of travel, or radially (from the center of the tire). Radial tire construction climbed to 100% market share in North America following
Consumer Reports
Consumer Reports (CR), formerly Consumers Union (CU), is an American nonprofit consumer organization dedicated to independent product testing, investigative journalism, consumer-oriented research, public education, and consumer advocacy.
Founded ...
finding the superiority of the radial design in 1968, and were standard by 1976.
History
The first radial tire designs were patented in 1914 by G.H. Hamilton and T. Sloper -patent № 467 filed in
London
London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
,
and in 1916 by
Arthur W. Savage, a tire manufacturer (1915–1919), firearm designer and inventor in
San Diego, CA
San Diego ( , ; ) is a city on the Pacific Ocean coast of Southern California located immediately adjacent to the Mexico–United States border. With a 2020 population of 1,386,932, it is the eighth most populous city in the United States ...
- . No actual products were created.
Michelin
Michelin (; ; full name: ) is a French multinational tyre manufacturing company based in Clermont-Ferrand in the Auvergne-Rhône-Alpes ''région'' of France. It is the second largest tyre manufacturer in the world behind Bridgestone and la ...
in
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
designed, developed, patented, and commercialized the radial tire.
The first Michelin X radial tire for cars was developed in 1946 by Michelin researcher Marius Mignol.
There is no evidence that the former accountant turned researcher Mignol had knowledge of Hamilton or Savage's earlier work when he began his experiments in 1941.
Michelin owned the leading automaker
Citroën
Citroën () is a French automobile brand. The "Automobiles Citroën" manufacturing company was founded in March 1919 by André Citroën. Citroën is owned by Stellantis since 2021 and previously was part of the PSA Group after Peugeot acquired ...
, so it was quickly able to introduce its new design, including on the new 1948
Citroën 2CV
The Citroën 2CV (french: link=no, deux chevaux(-vapeur), , lit. "two steam horse(power)s", meaning "two ''taxable'' horsepower") is an air-cooled front-engine, front-wheel-drive, economy family car, introduced at the 1948 Paris Mondial de l ...
model. In 1952, Michelin developed a radial truck tire.
Because of its significant advantages in durability and fuel economy, this technology spread quickly in Europe and Asia in the 1950s and 1960s.
In 1968, ''
Consumer Reports
Consumer Reports (CR), formerly Consumers Union (CU), is an American nonprofit consumer organization dedicated to independent product testing, investigative journalism, consumer-oriented research, public education, and consumer advocacy.
Founded ...
'', an influential American magazine, acknowledged the superiority of the radial tire design, documenting its longer tread life, better steering characteristics, and less rolling resistance, which increases
gas mileage
Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
.
[Consumer Reports, "Tires," Consumer Reports, (August 1968): 404-409.]
In 1970,
Ford Motor Company
Ford Motor Company (commonly known as Ford) is an American multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. The company sells automobi ...
produced the first
American-made vehicle with radial tires as standard equipment,
Michelin
Michelin (; ; full name: ) is a French multinational tyre manufacturing company based in Clermont-Ferrand in the Auvergne-Rhône-Alpes ''région'' of France. It is the second largest tyre manufacturer in the world behind Bridgestone and la ...
tires fitted to the
Continental Mark III.
In 1974,
Charles J. Pilliod, Jr.
Charles J. Pilliod Jr. (October 20, 1918 – April 18, 2016) was an American business executive and diplomat.
He was ambassador to Mexico from 1986 to 1989.
Biography
Pilliod served in World War II from 1942 to 1945 as a pilot in the 20th Air Fo ...
, the new CEO of
Goodyear Tire and Rubber Company
The Goodyear Tire & Rubber Company is an American multinational tire manufacturing company founded in 1898 by Frank Seiberling and based in Akron, Ohio. Goodyear manufactures tires for automobiles, commercial trucks, light trucks, motorcycles, S ...
, faced a major investment decision regarding retooling for the radial tire, following the
1973 oil crisis
The 1973 oil crisis or first oil crisis began in October 1973 when the members of the Organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had supp ...
. Despite heavy criticism at the time, Pilliod invested heavily in new factories and tooling to build the radial tire.
Today, only Goodyear,
Cooper
Cooper, Cooper's, Coopers and similar may refer to:
* Cooper (profession), a maker of wooden casks and other staved vessels
Arts and entertainment
* Cooper (producers), alias of Dutch producers Klubbheads
* Cooper (video game character), in ...
, Titan, and Specialty Tires of America remain independent among US tire manufacturers, and the radial has practically replaced all other construction methods for automobile tires on the market. Sam Gibara, who headed Goodyear from 1996 to 2003, has noted that without the action of Pilliod, Goodyear "wouldn't be around today."
In 1974,
Pirelli
Pirelli & C. S.p.A. is a multinational tyre manufacturer based in Milan, Italy. The company, which has been listed on the Milan Stock Exchange since 1922, is the 6th-largest tyre manufacturer and is focused on the consumer production of tyre ...
developed the ''wide radial tire'' on a request of the
Lancia
Lancia () is an Italian car manufacturer and a subsidiary of FCA Italy S.p.A., which is currently a Stellantis division. The present legal entity of Lancia was formed in January 2007 when its corporate parent reorganised its businesses, but it ...
rally racing team for a tire to handle the power of the new
Lancia Stratos
The Lancia Stratos HF (''Tipo 829''), widely and more simply known as Lancia Stratos, is a rear mid-engined sports car designed for rally racing, made by Italian car manufacturer Lancia. The HF stands for ''High Fidelity''. It was a very successf ...
and in the succeeding year, Pirelli introduced a wide tire with a reduced sidewall height like a slick, but with a radial construction for the
Monte Carlo Rally
The Monte Carlo Rally or Rallye Monte-Carlo (officially ''Rallye Automobile de Monte-Carlo'') is a rallying event organised each year by the Automobile Club de Monaco. The rally now takes place along the French Riviera in Monaco and southeast ...
winning works Stratos.
Radial technology is now the standard design for essentially all automotive tires.
Bias tires are still used on
trailers
Trailer may refer to: a
Transportation
* Trailer (vehicle), an unpowered vehicle pulled by a powered vehicle
** Bicycle trailer, a wheeled frame for hitching to a bicycle to tow cargo or passengers
** Full-trailer
** Semi-trailer
**Horse trailer ...
due to their weight carrying ability and resistance to swaying when towed.
For aircraft, the transition is happening more slowly, as tires are certified along with the
airframe
The mechanical structure of an aircraft is known as the airframe. This structure is typically considered to include the fuselage, undercarriage, empennage and wings, and excludes the propulsion system.
Airframe design is a field of aerospa ...
. A radial has less material in the sidewall, so it weighs less, runs cooler and lasts longer. For smaller planes, bias tires afford more stability at higher speeds and have stronger sidewalls.
Construction
A series of plies of
cord
Cord or CORD may refer to:
People
* Alex Cord (1933–2021), American actor and writer
* Chris Cord (born 1940), American racing driver
* Errett Lobban Cord (1894–1974) American industrialist
* Ronnie Cord (1943–1986), Brazilian singer
* Co ...
reinforces a tire. Without this, a tire would be flexible and weak. The network of cords that gives the tire strength and shape is called the carcass. Since the 1960s, all common tires have a carcass of cords of polyester, steel, or other textile materials, inlaid with several layers of rubber.
In the past, the fabric was built up on a flat steel drum, with the cords at angles of about +60 and −60 degrees from the direction of travel, so they criss-crossed over each other. They were called
cross ply
A cross is a geometrical figure consisting of two intersecting lines or bars, usually perpendicular to each other. The lines usually run vertically and horizontally. A cross of oblique lines, in the shape of the Latin letter X, is termed a sa ...
or bias ply tires. The plies were turned up around the steel wire beads and the combined tread/sidewall applied. The green (uncured) tire was loaded over a curing bladder and shaped into the mold. This shaping process caused the cords in the tire to assume an S-shape from bead to bead. The angle under the tread, the crown angle, stretched down to about 36 degrees. In the sidewall region the angle was 45 degrees, and in the bead it remained at 60 degrees. The low crown angle gave rigidity to support the tread and the high sidewall angle gave comfort. To increase strength, the manufacturer would increase the number of plies, and the
heat buildup in the tire.
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 tire's rolling friction. This allows vehicles with radial tires to achieve better
fuel economy than 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.
With only radial cords, a radial tire would not be sufficiently rigid at the contact with the ground. To add further stiffness, the entire tire is surrounded by additional belts oriented closer to the direction of travel, but usually at some "spiral" angle. These belts can be made of steel (hence the term steel-belted radial),
polyester
Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natural ...
, or
Aramid
Aramid fibers, short for aromatic polyamide, are a class of heat-resistant and strong synthetic fibers. They are used in aerospace and military applications, for ballistic-rated body armor fabric and ballistic composites, in marine cordage, ma ...
fibers such as
Twaron
Twaron (a brand name of Teijin Aramid) is a para-aramid. It is a heat-resistant and strong synthetic fibre developed in the early 1970s by the Dutch company Akzo Nobel's division Enka BV, later Akzo Industrial Fibers. The research name of the para ...
or
Kevlar
Kevlar (para-aramid) is a strong, heat-resistant synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, the high-strength material was first used commercially in the early 1970s a ...
.
In this way, low radial tires separate the tire carcass into two separate systems:
* The radial cords in the sidewall allow it to act like a spring, giving flexibility and ride comfort.
* The rigid steel belts reinforce the tread region, giving high mileage and performance.
Each system can then be individually optimized for best performance.
Application
Radial tires have different characteristics of springiness from those of
bias-ply tires, and a different degree of slip while steering. A benefit was that cars could now be made lighter because they would not have to make up for the deficiencies of bias-ply tires.
However, motorists were not accustomed to the feel, hence the suspension systems of cars had to be modified.
Ford Motor Company
Ford Motor Company (commonly known as Ford) is an American multinational automobile manufacturer headquartered in Dearborn, Michigan, United States. It was founded by Henry Ford and incorporated on June 16, 1903. The company sells automobi ...
engineer Jack Bajer experimented in the 1960s on a
Ford Falcon
Ford Falcon is an automobile nameplate applied to several vehicles worldwide.
* Ford Falcon (North America), an automobile produced by Ford from 1960 to 1970.
* Ford Falcon (Argentina), a car built by Ford Argentina from 1962 until 1991.
* Fo ...
, by giving it less tight steering, and adding both isolators to the drive shaft and
bushings to the suspension, the latter being to absorb the thump of riding over asphalt expansion joints in a concrete roadway.
Radial tires have occasionally found application on bicycles, used on the 1980s Miyata touring bicycle; models 1000 and 610, and more recently in 2009 on the
Maxxis
Cheng Shin Rubber Industry Co. () is a Taiwanese and the ninth largest tire company in the world. Established in 1967, in Yuanlin City, Changhua County, Taiwan, by Luo Jye. Maxxis Tyres and CST tires are wholly owned subsidiaries of Cheng Shin.
...
Radiale.
Panaracer radial tires were also standard on the Jamis Gentry model bicycle in 1985.
Features
The advantages of radial tires over bias ply:
* Flexible sidewalls
* Reduced fuel consumption due to less rolling resistance
* A softer ride because of the layout of the tire's plies and because of the flex of the sidewalls. This assumes equivalent profiles between the two tires (also, as stated above, at lower speeds radial-ply tires will react more harshly to ridges in the road such as expansion joints).
* More stable contact with the road surface.
* Steel belted – Results in tougher overall construction
* Longer tread life
* Wider footprint
* Less ground compaction and damage
* Reduction in tire replacement due to less heat generated by the tire.
* Reduced machine maintenance costs.
See also
*
Firestone 500 Radial tread separation/recall
References
External links
Michelin AG - Comparison of Bias vs Radial
{{DEFAULTSORT:Radial Tire
Tires
Friction
Vehicle technology