Dateline 3500 B.C.--Today, man invented the greatest invention ever seen, THE WHEEL!
Thousands of years later, the wheel has come a long way. For one thing it is no longer made of wood and it is guaranteed that the ride is much smoother. What hasn't changed is the fact that it is still one of man's greatest inventions. Could you imagine where we would be today without it?
The early wheel was very simple: a solid curved piece of wood. Later, leather was added to soften the ride. As time progressed it became solid rubber which led to today's tire--the pneumatic, or air inflated, radial tire.
The first wheels made of metal or wood were very durable but did not provide a very comfortable ride. The nearest thing to the first tire was a metal hoop. There were many individuals that made contributions in creating the tire as we think of it today.
Vulcanization and Charles Goodyear
Rubber was not always as useful as it is today. Early rubber did not hold shape; it would be sticky in hot weather and become inflexible in the cold.
In 1839 Charles Goodyear was credited with the discovery of the vulcanization process. Vulcanization is the process of heating rubber with sulfur. This transforms sticky raw rubber to firm pliable material which makes rubber a perfect material for tires.
The story of Charles Goodyear is a sad one. Although he dedicated his entire life to making rubber a better form, he would never profit from all his work. Charles Goodyear died bankrupt.
Forty years later, a rubber company would honor his hard work by using his name for their new tire company.
Solid Rubber Tires
Soon after the discovery of vulcanization, tires were made out of solid rubber. These tires were strong, absorbed shocks and resisted cuts and abrasions. Although they were a vast improvement, these tires were very heavy and did not provide a smooth ride.
Today there are still types of tires made of solid rubber.
The pneumatic tire uses rubber and enclosed air to reduce vibration and improve traction. Robert W. Thomson, a Scottish engineer, first patented the air-filled tire. Unfortunately the idea was too early for its time and was not a commercial success.
In 1888 John Boyd Dunlop of Belfast, Ireland, became the second inventor of the pneumatic tire. Dunlop claimed to have no knowledge of Thomson's earlier invention.
The second time around, the pneumatic tire caught the public's attention. The timing was perfect because bicycles were becoming extremely popular and the lighter tire provided a much better ride.
Bias Ply Tires
For the next fifty years, vehicle tires were made up of an inner tube that contained compressed air and an outer casing. This casing protected the inner tube and provided the tire with traction.
Layers called plies reinforced the casing. The plies were made of rubberized fabric cords that were embedded in the rubber. These tires were known as bias ply tires. They were named bias ply because the cords in a single ply run diagonally from the beads on one inner rim to the beads on the other. However, the orientation of the cords is reversed from ply to ply so that the cords crisscross each other.
Today you can still find bias-ply tires as authentic equipment for antique and collector cars, as well as for certain type of off-the-road tractor tires.
The first introduced steel-belted radial tires appeared in Europe in 1948. Radial tires are so named because the 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. The advantages of radial tires include longer tread life, better steering and less rolling resistance, which increases gas mileage. On the other hand, radials have a harder riding quality, and are about twice as expensive to make.