With the transition from horse and buggy to more modern modes of transportation, faster vehicles capable of longer distances of travel became the norm. The wheels on such vehicles obviously became quite important—the wood and metal constructs that initially performed well on wagons were not as well suited to automobiles, motorcycles, and bicycles.
Needing a material with added durability and also cushioning, early tire manufacturers turned to rubber. Initially composed of solid rubber, the first tires were durable, but also heavy and rough on roads.
Though it had been invented earlier, the pneumatic tire found a niche again in the early 1900s in the form of bicycle tires. The idea soon spread to cars, where the new inflatable tires were lighter and provided better shock absorption, allowing for a smoother ride. These early tires consisted of an inner inflatable tube paired with an outer tire that provided protection and traction. Not completely composed of rubber, these outer tires had alternating layers of rubberized cords, or plys, imbedded within them to provide some degree of reinforcement. Because these plys ran at an angle from the outer tire rim to the inner tire rim, they were referred to as bias-ply tires.
The Michelin company hit upon the next major advancement in the 1940s by producing the first radial-ply tire. In contrast to the bias-ply tire, the plys on a radial tire run at a ninety-degree angle to the tire rims, like the spokes of a bicycle wheel. Michelin also embedded a belt of steel mesh in the tire to further reinforce it. The new tires lasted longer, enhanced steering, and improved mileage, but were more costly to manufacture. Nevertheless, they have become the gold standard of the tire industry.
