What is a tire? “A tire 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 that the vehicle is on,” according to Wikipedia.
(Photo: Live Science)
First the wheel
To understand the history of tires, the evolution of the wheel must be reviewed. One of man’s greatest inventions, the wheel dates back to the Neolithic era – 3500 BC – or prior to the Bronze Age. The first wheels were made of wood and were likely used first to assist man with agricultural chores. Over time wheels were used for many purposes and were a key to human advancement.
However, one drawback of wheels was – and continues to be – wear and tear. The rotation of a wheel around a central axle helped carry heavy items and helped man move more quickly than ever before. However, wheels – whether made of wood or later of metal – slowly wore away over time and they did not wear evenly. A chip or uneven wear would cause a wheel to no longer be round, causing the time-consuming and expensive task of replacing something that wasn’t quite broken.
An expendable layer that could absorb damage, wear away over time and then be easily replaced at a much more affordable cost than a brand new wheel is what was needed. The answer was, and is, a tire.
What is the origin of the word “tire?” Going back to the 1300s, the word “tire” was a short form of “attire” – a wheel with a tire is a dressed wheel.
First leather, then metal
The earliest tires were bands of leather, then iron (later steel) that were placed on wooden wheels used on carts and wagons. A skilled wheelwright would expand the tire by heating it in a forge, place it over the wheel and then wet it, causing the metal to contract back to its original size so that it fit tightly on the wheel.
After the invention of the steam locomotive in Great Britain in the 1820s, the emergence of trains and railway networks followed, and steel “tires” were attached to metal train wheels. In the United States, metal tires were used on trains, but also on farm wagons, stagecoaches and the Conestoga wagons that helped to open up the West. The metal tires were long-lasting and inexpensive but not particularly reliable.
Vulcanization
In 1839, American inventor and entrepreneur Charles Goodyear was credited with the discovery of the vulcanization process. Within weeks of one another in 1845, British inventor Thomas Hancock and Charles Goodyear were awarded patents for the vulcanization of rubber. Named after Vulcan, the Roman god of fire, vulcanization “is a chemical process for converting natural rubber or related polymers into more durable materials by the addition of sulfur. Vulcanized materials are less sticky and have superior mechanical properties.” Vulcanization transforms sticky raw rubber into a firm, pliable material that makes rubber a perfect material for tires.
Vulcanization also made rubber waterproof and winter-proof, while at the same time preserving its elasticity. While Goodyear’s claim of inventing vulcanization was challenged, he prevailed in court and is today remembered as the sole inventor of vulcanized rubber.
However, the story of Charles Goodyear is a sad one. Although he dedicated his entire life to making rubber more useful, he never profited from all his work. Goodyear was bankrupt when he died; however, a company bearing his name – Goodyear Tire and Rubber Company – was founded in Akron, Ohio in 1898.
Solid rubber tires
Soon, after the use of vulcanization began, rubber became the material of choice for tires. These tires were strong, absorbed shocks and resisted cuts and abrasions. Although they were a vast improvement over wooden or metal tires, solid rubber tires were very heavy and did not provide a smooth ride.
Metal tires are still used on locomotives and railcars, and solid rubber (or other polymer) tires are still used in various non-automotive applications, such as some casters, carts, lawnmowers and wheelbarrows.
Pneumatic tires
The pneumatic, or inflatable, rubber tire uses rubber and enclosed air to reduce vibration and improve traction. The pneumatic tires that are used on millions of vehicles around the world are the result of multiple inventors working across several decades. And those inventors have names that should be recognizable to anyone who has ever purchased tires – Dunlop, Goodyear and Michelin.
Pneumatic tires are used on many types of vehicles, including cars, bicycles, motorcycles, buses, trucks, heavy equipment and aircraft. Pneumatic tires provide a flexible cushion that absorbs shock as the tire rolls over rough surfaces. Pneumatic tires provide a footprint that is designed to match the weight of the vehicle with the bearing strength of the surface that it rolls over.
Robert W. Thompson, a Scottish engineer, created and patented the first, air-filled tire in 1847. The tire used rubber and enclosed air to reduce vibration. The process was too costly, though, and his design was never put into production.
However, in 1888, another Scotsman, John Boyd Dunlop, developed the first successful pneumatic tire in Belfast, Ireland. Dunlop was already wealthy; he owned successful veterinary practices. However, after his son complained of his bicycle’s harsh ride because of its solid rubber tires, Dunlop started developing the tire.
His patent, granted in 1888, wasn’t for automobile tires, however. Instead, it was intended to create tires for bicycles.The pneumatic tire proved so successful that a year after it was introduced, it helped to win bicycle races in Ireland and England. Over the next few years, Dunlop developed pneumatic tires for all vehicles, from bicycles to the earliest cars and trucks. Between 1890-1920, rubber pneumatic tires were improved by Dunlop and by others such as Thomas Hancock.
It took another seven years for someone to make the leap from bicycle to the horseless carriage. In 1895, André Michelin and his brother, Edouard, who had previously patented a removable bike tire, were the first to use pneumatic tires on an automobile. Unfortunately, the tires were not durable enough. However, over time their company became one of the leading tire companies in the world.
According to ThoughtCo., “In 1903, P.W. Litchfield, who worked at Goodyear, patented the first tubeless tire.” However, it was never commercially exploited until used on the 1954 Packard. In 1904, mountable rims were introduced; they allowed drivers to fix their own flats. In 1908, Frank Seiberling (who also founded a tire company) invented grooved tires. The grooves dramatically improved road traction. According to ThoughtCo., “in 1910, the B.F. Goodrich Company invented longer-life tires by adding carbon to the rubber.” Philip Strauss invented the combination tire and air-filled inner tube in 1911; this invention allowed pneumatic tires to be used successfully on automobiles. His company, the Hardman Tire & Rubber Company, marketed the tires.
The balloon tire, a low-pressure tire that had a greater contact area with the road surface, was introduced in 1923. The first winter tires or snow tires for trucks were introduced in Finland in 1934.
Bias-plies and radial tires
By the 1920s, the German chemical company Bayer had developed synthetic rubber; it began to be widely used to manufacture tires. For the next few decades, bias-ply tires were widely manufactured. These tires had two separate parts: an inflated inner tube; and the outside tire, or casing. The inner tube was pressurized and was protected by the outer casing. This casing protected the inner tube and provided the tire with traction. The outer casing was made of layers, which reinforced the casing. Each layer was called a ply. The plies were made of rubberized fabric cords that were embedded in the rubber. These bias-ply tires had a single ply that ran diagonally from the beads on one inner rim to the beads on the other. The orientation of the cords is reversed from ply to ply so that the cords criss-crossed each other. Bias-ply tires were the primary type of tires for the next 50 years.
Bias-ply tires are still used as authentic equipment for antique and collector cars, as well as for certain types of off-road tractor tires.
Radial tires
After World War II, French tire manufacturer Michelin developed radial tires, which far outperformed the bias-ply tires. Although the use of radial tires spread quickly throughout Europe and Asia (it boasted superior handling and fuel economy numbers), the outdated bias-ply tire construction persisted in the United States. Then, in 1968, Consumer Reports awarded radials its two top spots in its report on the best tires. The magazine cited longer life, increased safety, handling, and noted that in the long run, the costs of running on radials was far less than bias-ply tires, which needed to be replaced quite often. Ford Motor Company adopted radial tires in the early 1970s. Today, radial tires currently have nearly a 100% market share.
Steel-belted radial tires’ ply cords radiate at a 90-degree angle from the wheel rim, and the casing is strengthened by a belt of steel fabric that runs around the circumference of the tire. Radial tire ply cords are made of nylon, rayon or polyester. Radial tires’ advantages include longer tread life, better steering and less rolling resistance, which increases gas mileage. However, radials have a harder riding quality, and are about twice as expensive to manufacture.
Other improvements and changes
Tubeless tires were developed in 1947. Tubeless tires contributed to the reduction of the vehicle’s weight, allowing for a significant savings in fuel costs.
Run-flat tires were developed in the late 1970s and early 1980s to help drivers maintain a constant driving speed and avoid accidents caused by dramatic loss of air pressure. The run-flat tire allows vehicles to continue driving up to 50 miles at 50 mph with a punctured tire.
Several types of tires were designed later, including eco-friendly tires as well as the ultra high performance (UHP) tire. UHP tires have diameters greater than 16 inches and allow for superior cornering, braking and drivability.
Since 2007, all U.S. vehicles must be equipped with tire pressure monitoring systems (TPMS). After a huge recall of Firestone tires in the 1990s, Congress mandated the use of TPMS on passenger vehicles to warn drivers of underinflated tires.
Currently, tire companies are working on a non-pneumatic tire created from a uni-material that can be reused or recycled. These airless tires are believed by many to be the tires of the future.
Perhaps one of the biggest changes over the last 100 years is the decline of the U.S. tire industry. Particularly over the last three decades, the U.S. tire industry lost market share and many of the largest U.S. tire manufacturers were bought by Japanese and European manufacturers.
This truck has tires that are in good condition (and a spare). (Photo: Shutterstock)
Truck tires
Just as automobiles have improved since they were first introduced, so have trucks. The earliest trucks were much smaller and carried much lighter loads than trucks today. But as trucks grew in size and load weight – as well as specialization (dry vans, refrigerated trailers, etc.) – heavy-duty tires had to be developed.
Tires for large trucks and buses are made in a variety of sizes and profiles. Today’s truck tires carry loads between 4,000 to 5,500 pounds on the drive wheel. These tires are usually mounted in tandem on the drive axle.
Truck tires come in a variety of profiles that include “low profile,” “wide-base” for the heaviest vehicles, and a “super-single” tire that has the same total contact pressure as a dual-mounted tire combination.
Off-road tires are manufactured for use on construction vehicles, agricultural and forestry equipment and other applications that take place on soft terrain. Tires designed for soft terrain have deep, wide treads to provide traction in loose dirt, mud, sand or gravel. Off-road tires are also built for machinery that travels over hardened surfaces at industrial sites, ports and airports.
Retreads are a popular option for many truck fleets. (Photo: Service Truck Tire Centers)
Retreads
When vehicles were first equipped with pneumatic tires back in the early 1900s, among the most challenging problems was getting the tires to withstand cuts, punctures, penetrations and blowouts. Those early pneumatic tires – even tires in excellent shape – would only average about 1,000 miles before wearing out. However, because the roads were unpaved and had hazards of all types, most tires did not even last for 1,000 miles.
As a result, people started to investigate ways to extend tire life. That led to the practice of tire retreading.
Retreading origins
There were various forms of retreading tested in the early 1900s. One method was to apply several layers of uncured rubber to the tire. A third circle mold was used to vulcanize one-third of the tire at a time until the complete tire was cured. The primary problem with this method was that moving sections around in the mold led to uneven curing. It was also difficult to control the temperature of the rubber. In addition, molds weren’t available for every size of tire on the market.
Marion Oliver developed and patented a tire retreading method known as pre-cured treads in 1912. Oliver’s process was labor-intensive and difficult, however.
Increasing demand led to continued improvements
The number of automobiles in the U.S. grew from 500,000 to eight million by 1921. Retreads have been around almost as long as modern tires themselves. Retreads started as a cost-effective method of reusing good quality tire casings. The development of retreads is attributed to Marion Oliver, who developed and patented pre-cured treads in 1912. Retreading innovations and improvements were developed, including extruders to apply pre-heated, uncured rubber to a buffed, cemented tire, the invention of the full-circle mold to accommodate several sizes of tires and the use of airbags that pushed the tire against the mold, replacing solid iron cores and therefore improving the quality of the mold cure tire retreading process.
Industry growth
With increased demand, the retreading industry grew. In addition, the use of retreads grew during the Great Depression because of reduced incomes. Also, a decline in rubber prices made retreads more affordable. Major tire companies began entering the industry as the processes used to retread tires improved.
After synthetic rubber was invented to replace natural rubber, it was used extensively in retread stock. Also, because of rubber and synthetic rubber rationing during World War II, between 1942-1944 the tire retreading industry grew by 500%. The U.S. armed forces also relied heavily on retread tires during the war.
Trucks on the road. No matter what size truck, they all need tires. (Photo: saferoads.org)
Ongoing innovation
As improvements in synthetic rubber production and the availability of natural rubber increased, the tire retreading industry continued to grow and flourish. Electrically heated molds were introduced, enabling smaller retread operations to invest in individual molds and gradually expand their production. Significant improvements were also made to buffing rasps and by the end of the 1940s there were close to 9,500 retread shops in business.
Over the next several decades, retreaders were forced to meet new and changing challenges, including the adoption of tubeless technology, and the use of tire venting and inner liner spraying to detect and prevent casing separation. Additionally, the use of an envelope replaced metal banding in the curing process. The introduction and increased use of radial tires ultimately changed the face of American tire retreading.
Globalization and high-tech advances
In the 1980s, globalization in tire retreading was being embraced by more and more companies, and this was reflected in the dwindling number of U.S. retreaders. By 1989, the number of retread plants in the U.S. dropped to 2,100.
However, in the 1990s, a growth surge in the industry was spurred by the introduction of high-tech, computer-controlled tire retreading equipment. Also, the use of ultrasound and x-ray technology also became available and more widely adopted by retreaders. The result has been higher-speed production and enhanced testing capabilities. Other techniques, like computer-controlled buffing, building and extruding, have also changed the face of tire treading for the better. And, because of state-of-the-art compounding, today’s recapped tires last longer, run cooler and maintain a greater resistance to irregular wear.
FreightWaves Classics thanks the following websites for information used in this article: Tire Recappers; Wikipedia; ThoughtCo.; Theinventors.org; Burt Brothers Tire & Service; and Pixabay/Falkenpost.