A radial tire (more properly, a radial-ply tire) is a particular design of vehicular tire. 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 finding the superiority of the radial design in 1968, and were standard by 1976. [1] [2]
The first radial tire designs were patented in 1914 by G.H. Hamilton and T. Sloper -patent № 467 filed in London, [3] and in 1916 by Arthur W. Savage, a tire manufacturer (1915–1919), firearm designer and inventor in San Diego, CA - U.S. patent 1,203,910 . [4] [5] No actual products were created. [6]
Michelin in France designed, developed, patented, and commercialized the radial tire. [7] The first Michelin X radial tire for cars was developed in 1946 by Michelin researcher Marius Mignol. [7] 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. [3]
Michelin owned the leading automaker Citroën, so it was quickly able to introduce its new design, including on the new 1948 Citroën 2CV model. [8] In 1952, Michelin developed a radial truck tire. [9]
Because of its significant advantages in durability and fuel economy, [10] this technology spread quickly in Europe and Asia in the 1950s and 1960s. [7] [11] [1]
In 1968, Consumer Reports , 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 improves fuel economy. [12] [13]
In 1970, Ford Motor Company produced the first American-made vehicle with radial tires as standard equipment, Michelin tires fitted to the Continental Mark III. [14]
In 1974, Charles J. Pilliod, Jr., the new CEO of Goodyear Tire and Rubber Company, faced a major investment decision regarding retooling for the radial tire, following the 1973 oil crisis. Despite heavy criticism at the time, Pilliod invested heavily in new factories and tooling to build the radial tire. [15] Today, only Goodyear, Cooper, 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." [15]
In 1974, Pirelli developed the wide radial tire on a request of the Lancia rally racing team for a tire to handle the power of the new Lancia Stratos 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 winning works Stratos. [16]
Radial technology is now the standard design for essentially all automotive tires. [1]
Bias tires are still used on trailers due to their weight carrying ability and resistance to swaying when towed. [17]
For aircraft, the transition is happening more slowly, as tires are certified along with the airframe. A radial has less material in the sidewall, so it weighs less, runs cooler and lasts longer. [18] For smaller planes, bias tires afford more stability at higher speeds and have stronger sidewalls. [19]
A series of plies of cord 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 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. [20]
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, or Aramid fibers such as Twaron or Kevlar.
In this way, low radial tires separate the tire carcass into two separate systems:
Each system can then be individually optimized for best performance.
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. [21]
However, motorists were not accustomed to the feel, hence the suspension systems of cars had to be modified. Ford Motor Company engineer Jack Bajer experimented in the 1960s on a Ford Falcon, 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, [22] and more recently in 2009 on the Maxxis Radiale. [23] Panaracer radial tires were also standard on the Jamis Gentry model bicycle in 1985.
The advantages of radial tires over bias ply: [12]
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
Michelin, in full Compagnie Générale des Établissements Michelin SCA, 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 larger than both Goodyear and Continental. In addition to the Michelin brand, it also owns the Kléber tyres company, Uniroyal-Goodrich Tire Company, SASCAR, Bookatable and Camso brands. Michelin is also notable for its Red and Green travel guides, its roadmaps, the Michelin stars that the Red Guide awards to restaurants for their cooking, and for its company mascot Bibendum, colloquially known as the Michelin Man, who is a humanoid consisting of tyres.
The Goodyear Tire & Rubber Company is an American multinational tire manufacturer headquartered in Akron, Ohio. Goodyear manufactures tires for passenger vehicles, aviation, commercial trucks, military and police vehicles, motorcycles, RVs, race cars, and heavy off-road machinery. It also licenses the Goodyear brand to bicycle tires manufacturers, returning from a break in production between 1976 and 2015. As of 2017, Goodyear is one of the top four tire manufacturers along with Bridgestone (Japan), Michelin (France), and Continental (Germany).
The rim is the "outer edge of a wheel, holding the tire". It makes up the outer circular design of the wheel on which the inside edge of the tire is mounted on vehicles such as automobiles. For example, on a bicycle wheel the rim is a large hoop attached to the outer ends of the spokes of the wheel that holds the tire and tube. In cross-section, the rim is deep in the center and shallow at the outer edges, thus forming a "U" shape that supports the bead of the tire casing.
A run-flat tire is a pneumatic vehicle tire designed to resist the effects of deflation when punctured, allowing the vehicle to continue to be driven at reduced speeds for limited distances. First developed by tire manufacturer Michelin in the 1930s, run-flat tires were introduced to the public market in the 1980s. They have increased in popularity over time.
Charles J. Pilliod Jr. was an American business executive and diplomat. He was ambassador to Mexico from 1986 to 1989.
Radial force variation or road force variation (RFV) is a property of a tire that affects steering, traction, braking and load support. High values of RFV for a given tire reflect a high level of manufacturing variations in the tire structure that will impart ride disturbances into the vehicle in the vertical direction. RFV is measured according to processes specified by the ASTM International in ASTM F1806 – Standard Practice for Tire Testing.
Automotive tires are described by an alphanumeric tire code or tyre code, which is generally molded into the sidewall of the tire. This code specifies the dimensions of the tire, and some of its key limitations, such as load-bearing ability, and maximum speed. Sometimes the inner sidewall contains information not included on the outer sidewall, and vice versa.
Pneumatic tires are manufactured according to relatively standardized processes and machinery, in around 455 tire factories in the world. With over 1 billion tires manufactured worldwide annually, the tire industry is a major consumer of natural rubber. Tire factories start with bulk raw materials such as synthetic rubber, carbon black, and chemicals and produce numerous specialized components that are assembled and cured.
The Goodyear Polyglas tire was a bias-belted tire announced in 1967 by Goodyear. "Polyglas" was a registered trademark. The tire combined some characteristics of both bias-ply and radial-ply tires. They had a wider tread than most other tires on the market then and used fiberglass belts.
Coker Tire Company is a Chattanooga, Tennessee-based company that manufactures and sells vintage-style Michelin, Firestone, BF Goodrich and Uniroyal bias-ply and radial whitewall tires for collector automobiles. The company was originally a tire and service center founded in 1958 by Harold Coker. He would later give his son Corky Coker the opportunity to manage the antique division, which was a small percentage of the company's earnings. Corky devoted 40 years to growing the antique division of the business, eventually making it the company's primary focus. Corky retired in 2014, and he appointed Wade Kawasaki as President to oversee the operations of six companies and numerous brands under the Coker Group. In November 2018, Corky sold Coker Tire and its parent company, Coker Group, to Irving Place Capital.
Tire uniformity refers to the dynamic mechanical properties of pneumatic tires as strictly defined by a set of measurement standards and test conditions accepted by global tire and car makers.
A bead breaker is a tool used for separating tires from rims. The innermost diameter of the tire that interfaces with the rim of a wheel is called the tire bead. The bead is a thicker section of rubber, and is reinforced with braided steel cables, called the bead bundle. The surface of the bead creates a seal between the tire and rim on radial and bias-ply tires.
The Michelin TRX, (and the related TDX), is a radial tire introduced by the Michelin Group in 1975. It is one of the first volume-produced low-profile tires. Although technologically advanced, and reasonably successful, the tire's requirement for a non-standard rim ultimately condemned it to a relatively short commercial life. It has thus been called the "Betamax of the tire industry."
Formula One tyres are specialised racing tyres designed for use on a Formula One car. These tyres play a crucial role in the car's performance, affecting grip, handling, and overall speed. The tyres have undergone major changes throughout the history of Formula One with different manufacturers and specifications used in the sport.
A bicycle tire is a tire that fits on the wheel of a bicycle or similar vehicle. These tires may also be used on tricycles, wheelchairs, and handcycles, frequently for racing. Bicycle tires provide an important source of suspension, generate the lateral forces necessary for balancing and turning, and generate the longitudinal forces necessary for propulsion and braking. Although the use of a pneumatic tire greatly reduces rolling resistance compared to the use of a rigid wheel or solid tire, the tires are still typically the second largest source, after wind resistance, of power consumption on a level road. The modern detachable pneumatic bicycle tire contributed to the popularity and eventual dominance of the safety bicycle.
The Michelin PAX is an automobile run-flat tire system that utilizes a special type of rim and tire to allow temporary use of a wheel if its tire is punctured. The core of Michelin's PAX system is the semi-rigid ring installed onto the rim using special equipment. It provides support to the tire and its sidewall to allow emergency operation at limited speed until such time as the tire can be replaced. Cars that use the system include supercars like the Bugatti Veyron EB 16.4, luxury cars like the Rolls-Royce Phantom, and more common vehicles like the Honda Odyssey and Nissan Quest.
A motorcycle tyre is the outer part of motorcycle wheel, attached to the rim, providing traction, resisting wear, absorbing surface irregularities, and allowing the motorcycle to turn via countersteering. The two tyres' contact patches are the motorcycle's connection to the ground, and so are fundamental to the motorcycle's suspension behaviour, and critically affect safety, braking, fuel economy, noise, and rider comfort.
The Pirelli Cinturato is a Pirelli-developed car tyre that was the first example of a wrap-around radial tyre structure. It was used to good effect in motorsport, and most modern tyres are based upon the design. The five-times Formula One World Champion Juan Manuel Fangio called the Pirelli Cinturato "Extraordinary" and raced on it many times in the remainder of his career.
In motorsports, a tire war occurs when more than one manufacturer provides tires for a motorsports series. Historically, tire wars have occurred in many high-level series, such as Formula One, NASCAR, Super GT, and MotoGP.
