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INVENTORS AND INVENTIONS
John Boyd Dunlop
PNEUMATIC VEHICLE TIRES

The wheel was invented around 3500 BC. Thousands of years later, the wheel is no longer made of wood, and the ride is much smoother. This is because of the pneumatic tire, developed by John Boyd Dunlop from Scotland.

Charles Goodyear invented vulcanized rubber in 1839 when he developed the vulcanization process, which made rubber more pliable and increased its rigidity and durability, allowing rubber to be used for a much wider array of purposes. Soon after the discovery of vulcanization, vehicle tires began to be made of solid rubber, and they were strong, absorbed shocks, and resisted cuts and abrasions. However, these solid tires were very heavy and failed to provide a smooth ride over the rough roads of the day.

In October 1887, John Boyd Dunlop developed the first practical pneumatic or inflatable tire. He put an experimental tire he built on his son’s tricycle in the yard of his home in Belfast, Northern Ireland, after fitting the tire to a wooden disc 96 cm across. He made his first tires by wrapping the solid rubber tires on his son's tricycle with glued rubber sheets, and filled the cavity with air.

He took this wheel and a metal wheel from his son’s tricycle, and rolled both of them across the yard together. The metal wheel stopped rolling, but the pneumatic wheel continued until it hit a gatepost and rebounded off the post. Dunlop then placed pneumatic tires on both rear wheels of his son's tricycle, and the tricycle's rolling improved. He then constructed larger tires for bicycles with even more startling results.

He began testing his pneumatic tires at a sports ground in Belfast, and obtained a patent on his pneumatic tires on December 7, 1888. However, completely unknown to Dunlop, another Scotsman, Robert William Thompson from Stonehaven, had patented a pneumatic tire in 1847. Thompson had earlier placed his tires on horse‐drawn carriages in London, but they never caught on, because at the time they were too expensive to manufacture. Frustrated with this result, Thompson turned to solid rubber tires for his future inventions. Hence, it might be said that John Dunlop “reinvented” the pneumatic tire.

In 1889, William Hume won a bicycle race in Ireland using Dunlop tires for the first time, and he subsequently won more races in England. Hume was the first member of the public to purchase a bicycle fitted with pneumatic tires, after Dunlop suggested that Hume use them in a race. On May 18, 1889, Hume won all four cycling events at the Queen’s College Sports Event in Belfast. A short time later, in Liverpool, he won all but one of the cycling events, lifting inflatable tires into the spotlight, and making them the standard for bicycles. Losers in the Liverpool event included the sons of the head of the Irish Cyclist Association, Harvey Du Cros. Du Cros saw an opportunity, and proceeded to build a personal relationship with Dunlop. Together, they formed a company, which acquired the rights to Dunlop’s patent.

Two years after Dunlop was awarded his patent, he was officially informed in 1891 that his patent was invalid, based on Thompson’s earlier patent, which issued in France in 1846 and in the United States in 1847. However, Dunlop and Du Cros continued to capitalize on pneumatic tires for bicycles, and they acquired a Dublin company and renamed it Pneumatic Tyre and Booth's Cycle Agency. Dunlop retired in 1895, and Du Cros sold the entire bicycle tire business in 1896 to a British financier, Terah Hooley, for £3 million. Hooley then made improvements, and resold the company to the public for £5 million. Du Cros remained head of the business until he died. Early in the twentieth century, the company was renamed Dunlop Rubber.

The production of automobile tires did not begin until 1900, well after Dunlop’s retirement. As a result, Dunlop did not acquire any considerable remuneration from his invention.

Inflatable tires provide a smoother ride and increased traction since the wheel deforms slightly when it meets the road, creating a friction bond between the vehicle and the road as the tire deforms and casts a wider and longer footprint. This is in contrast with solid rubber tires, which do not deform. For reasons that do not appear as clear as they should, solid rubber tires remain the material of choice for tricycle wheels, while today inflatable tires are the choice for bicycles and most other vehicles worldwide. At the time Dunlop came up with his invention, bicycles were becoming extremely popular, and the lighter, air‐filled tire resulted in a better ride with less vibration.

For 50 years after Dunlop’s invention, vehicle tires were made using an inner tube containing compressed air and an outer casing. The casing protected the inner tube and provided the tire with traction. The tire casing was reinforced with layers comprising rubberized fabric cords embedded in the rubber, and these were known as “bias ply tires,” since the cords in the single ply ran diagonally from the bead of one inner rim to the bead on another rim. The orientation of the cords is reversed from ply to ply, so the cords crisscross each other. Today, you can still find bias ply tires as equipment for antique and collector cars, and for various types of off‐road tractor tires. In 1948, steel‐belted radial tires appeared in Europe, and are so named because the ply cords radiate at a 90° angle from the wheel rim, such that the casing is strengthened by a belt of steel fabric extending around the circumference of the tire. Radial tire ply cords are composed of nylon, rayon, or polyester. The advantages of radial tires include longer tread life, improved steering, and less rolling resistance, which results in increased gas mileage. On the negative side, radial tires have a harder riding quality, and are also about twice as expensive to make as previous pneumatic tires.