Basic Information
Tires are the donut-shaped things that fit around wheels to provide extra traction. They also absorb shock and protect the wheels.
Tires on Wagon Wheels
Old wagon wheels had metal tires, made of iron or steel. The metal was put on hot by a Wagonwright. It was then quenched in water, which would make the metal contract tight around the wheel. This gave a lot of strength and durability that a purely wooden wheel would lack.
Modern Pneumatic Tires
Modern tires are pneumatic (filled with air). This provides additional absorption of shock, and helps keep the tire in contact with the ground at all times, for a significant boost to traction.
Pneumatic tires are made of vulcanized rubber, which was invented by Charles Goodyear in 1839. Such tires did not become popular until the 1870s.
Prior to World War Two, vulcanized rubber tires were made by adding sulfur to a resin extract from the rubber tree. During WWII, most of the world's rubber trees were under Japanese control, so both the Unites States and Germany put funds towards inventing a synthetic version. Ever since, most vulcanized rubber has been made from sulfur and butadeine, a highly explosive, carcinogenic compound refined from crude oil.
Giant Molecule
One of the neat things about vulcanized rubber is that it melds together into giant molecular chains. Each car tire is actually a single enormous molecule. Unlike metal that you can just beat into a new shape, the tire's shape is set for life. The downside of this is that nothing in nature currently knows how to digest such a huge uber-molecule. Ultraviolet light and ozone can degrade tires, but newer tires have been laced with chemicals to prevent that. Until something new evolves to eat them, tires will live forever. In the US, we throw away an average of one tire per citizen per year.
Sources
Game and Story Use
- A thrown or damaged tire can slow down a vehicle. Damaged tires mean less traction, making it unstable and hard to drive. It can also put undue pressure on the wheels, axle or other parts of the car.
- Which means it's a wonderful complication to throw into the middle of a chase scene or vehicular combat.
- In a campaign set in the 19th Century, wagons and early automobiles might have metal or pneumatic tires. The former provides greater durability, but the later should result in better handling and faster speeds. Depending on how abstract the vehicle and chase rules are, this might matter.
- A time traveler from an alternate future where the Axis won travels back to the US during WW2 to give the beleaguered allies the formula to synthetic rubber.
- In the future, the world is cluttered with trillions of discarded tires. A Mad Scientist with an ecological agenda unleashes a tire-eating nanite to solve the problem. Of course, things go wrong, and all the world's tires are consumed, including those on moving cars, those used in the walls of earthships, tire swings, etc.
- After The End, if mutant equivalents of fantasy monsters exist, one might be a rubber-eater.
