History of the Wheel
Researchers agreed that 3500 BC is the year when the wheel was invented, which is more of a ballpark than an exact year. The place is Mesopotamia, the area now occupied by war-ravaged Iraq. The first wheel for transportation purposes is approximated to 3200 BC, its purpose being to move the Mesopotamian chariots.
To be completely historic, as noted here, the very beginning of the wheel goes back to the Paleolithic era (15,000 to 750,000 years ago).
Back then, humans used logs to move large loads around. The main problem with this method of transportation was that many rollers were required, and care was required to insure that the rollers stayed true to their course. One theory as to how this obstacle was overcome suggests a platform, or sledge, was built with cross-bars fitted to the underside, thereby preventing the rollers from slipping out from under the load. Two rollers would be utilized, with two cross-bars for each roller, one fore and the other aft of the roller.
The first iron rims around the wheel were seen on Celtic chariots in 1000 BC. The spoked wheel remained pretty much the same until 1802, when G.F. Bauer registered a patent for the first wire tension spoke. This wire spoke consisted of a length of wire threaded through the rim of the wheel and secured at both ends to the hub. Over the next few years, this wire spoke evolved into the round tension spoke we see on bicycles today.
Another major invention that came about the same with the wire tension spoke was the pneumatic tire, which was first patented in 1845 by R.W. Thompson. His idea was further improved in 1888 by John Dunlop, a Scottish veterinarian, who also patented it. Thanks to the smooth ride, Dunlop's tire replaced the hard rubber used by all bicycles at that time.
It's fair to start talking about automobile wheels starting with Karl Benz's 1885 Benz Patent Motorwagen. The three-wheel vehicle used bicycle-like wire wheels, which were fitted with hard rubber.
Speaking of rubber, the first people who thought about using it for automobile purposes were André and Edouard Michelin, who later founded the famous tire company. In 1910, the B.F. Goodrich Company invented longer life tires by adding carbon to the rubber.
Overseas, Ford's Model T used wooden artillery wheels, which were followed in 1926 and 1927 by steel welded-spoke wheels. Unlike Karl Benz's first vehicle, the car that "put America on wheels" had pneumatic tires invented by Mr. Dunlop. There was, however, a big difference between those tires and the ones we used today. Made of white carbonless rubber, the tire had a life expectancy of around 2000 miles. A tire only lasted for around 30 or 40 miles before it needed repairs. Common problems included: the tire coming off the wheel, punctures and the tube being pinched.
Paradoxically, the next step in wheel evolution was the disc one, which bears more resemblance to the initial solid designs. As with many other things in our history, the change was prompted by lower costs as the steel disc wheels were cheaper to make. The rim could be rolled out of a straight strip of metal, and the disc itself could be stamped from sheet metal in one easy motion. The two components were welded or riveted together, and the resulting wheel was one that was relatively light, stiff, resistant to damage, easily produced in mass quantities, and most important, cheaply produced.
Coming back to our story, today there are basically two types of wheels for automotive use, steel and alloy, both of which have benefited from the technological advancements. As a result, the massive, heavy wheels of the early automobile days have become lightweight, strong spoked units. It's worth noting that just as the first solid wheels turned to the spoked design in the relatively early stages of humanity, so did in the 20th century.
Though we won't get too technical about the differences between steel and alloy wheels, we will say that the latter are lighter and better heat conductors. As a result, cars fitted with alloy wheels sport improved steering and handling and prolong the life of the brakes. They are also more visually appealing, but that's another story. On the other hand, alloy wheels are considerably more expensive to make than steel ones, which raises the overall price of the car.
As the traditional wheel design is close to exhausting any possible development, companies are looking at more and more exotic prototypes to replace it. Among these, Michelin is probably the most active in the field of research with two recent innovative concepts, the Tweel and the Active Wheel System.
Announced in 2006, the Tweel returns to the first designs by using a non-pneumatic solution instead of the traditional tire and wheel combination. The rolling surface consists of a rubber tread, which is bonded to the hub via flexible spokes. The flexible spokes are fused with a deformable wheel that absorbs shocks and rebounds. Michelin claims that even without the air needed in conventional tires, the Tweel still delivers pneumatic-like load-carrying capacity, ride comfort and resistance to road hazards.
Active Wheel System
The concept is probably the most revolutionary of them all as it incorporates all of the car's key components into the wheel itself. While only suitable for electric cars, the Active Wheel System houses the engine, the suspension, the gearbox and the transmission shaft.