Tire
A tire (British tyre) is the part of a wheel which is made of rubber. There are tires on many vehicles, such as cars, airplanes, bicycles, wheelbarrows and other things that need to move around smoothly.
Tires need to be changed after their treads wear away. Driving with worn tires is very dangerous. It can cause the tire to explode and the driver to lose control.
Construction
Tires are made of different types of rubber. Softer rubber is used in summer or when the tires need better traction, for example, in auto racing. Tires made of harder rubber are made for long lasting performance. There are many different types of tires. They come in different sizes and have different tread patterns.
There are many different sizes of tires. They are marked with 3 numbers and might look like: 225/60R16. The first number is the width in millimeters of the tire at the widest point when it is mounted and inflated. The second number is the sidewall (side of the tire) height as a ratio or percentage of the width. The last number is the wheel diameter in inches.
- Example
Tire size: 225/60R16
- Tire width = 225mm
- Sidewall height = 135mm (225 * .60 = 135)
- Wheel diameter = 16 inches
Very large tires (for example, tires on big mining trucks) use different units. For example: 59/80R63. The first number is the width in inches of the tire. The second number is the sidewall height as a ratio of the width. The last number is the wheel diameter in inches.
Tire damage
Most tires today do not have a tube inside of them. There are grooves in the wheel that let the tire be popped into place and hold a lot of air pressure. If there is a crack in the tire, it will not be able to hold its air. Tire leaks are very common. The most common cause is a hole from a nail or screw. This can usually be fixed by patching the inside of the tire so that it can hold air again. If the hole is close to or in the side of the tire, it can not be fixed. This is because the sides of the tire flexes to support the weight of the vehicle. A patch will not be able to handle the stress.