What are their sizes, how are they constructed, and why do they need wear and tear or do they have to be partially burned during landing?
At a glance, aircraft tires seem quite small compared to the total size of an aircraft. However, in reality, aircraft tires are much larger when compared to normal car tires. For example, the tires of a Boeing 737 are up to 27/7.75-R15 in inches, meaning they have a diameter of 685.8 mm, a width of 196.85 mm and a rim size of 381 mm.
Michelin aircraft tire construction.
About the chemical composition is similar. The complete aircraft tire is made up of four basic materials: rubber, nylon, some special wire, and steel. The rubber here is usually natural rubber, because they have better specifications, such as the ability to disperse heat. However, in terms of texture, it is formed by a process called vulcanization, with many overlapping layers such as nylon, Kevlar… Technical standards for hardness, durability, abrasion… It is also more stringent than normal tire production standards, even compared to supercars or sports racing tires.
The gas injected into the tire will be an inert gas such as nitrogen, to minimize the rise and fall of tire pressure due to temperature. Because if it contains a lot of air, water vapor combined with high temperature and pressure when landing will cause it to automatically explode when it reaches the limit point. And another thing is that the inert gas also helps prevent corrosion on the inner side of the rim.
PSI stands for Poundper Square Inch – which means the pressure in Pounds exerted per Square Inch. And according to reports, airplane tires are inflated to about 200 psi, 6 times the psi of the average car tire. In fact, according to an experiment recorded by National Geographic, the tires of a Boeing 737 can withstand more than 900 psi of pressure before exploding.
This design is to prevent Hydroplaning or Aquaplaning situations, which occur while the tires are moving on a slippery road surface in the rain. These longitudinal grooves also provide better grip between the runway surface and the aircraft’s tires, providing directional stability and aiding braking. If you use cubes in the form commonly found on car tires, they will simply break under the pressure of landing.
And all airliner tires don’t need some diagonal grooves or other textures to trigger or aid in changing direction when traveling like on other vehicles.
As soon as the plane lands, at the first moment, the tires will slide instead of rolling. The plane will drag them along the runway until the tire’s rotational velocity matches the plane’s speed. This is why airplane tires often smoke when landing and this also wears down some of its rubber on the runway. To make this possible, modern anti-lock braking systems designed specifically for aircraft will squeeze and release the brakes hundreds of times per second, in order to reduce the landing distance to a minimum.
Most of the normal tire wear comes from landing. The rubber on the tire will be partially ignited until the tire rotates at a rotational speed that matches the ground speed of the aircraft. This causes large smoke and wears out part of its rubber, leaving it on the runway. Airports often use high-pressure water or chemicals to remove this rubber.
An average aircraft tire can make about 450-500 landings before needing to redo the grooves. A tire can be re-grooved 7 times over its life. Tire changes can take anywhere from 40 minutes to two hours.
In practice, however, each tire manufacturer has specific wear and tear criteria to determine when an aircraft needs a tire change. Sometimes, unusual problems appear on the tire body such as cracks, breakage, special wear… and they can be replaced immediately.
Even when not in use, the aircraft still needs periodic tire changes. In addition, the outside temperature also affects the life of the tire, for example, airplanes often have to fly over the sea, or often have to land at high-temperature airports near the desert, with runways often having sandy.
Depending on the aircraft type, manufacturer and other criteria, the price of aircraft tires varies from a few tens of dollars, a few hundred dollars to several thousand dollars each.
So, if you want to know the detailed price of a tire in a specific location on the fuselage, you need to get the serial number on the tire and ask the airline’s purchasing department. Prices will also vary if you or the airlines have a long-term contract with the tire company.
Yes of course. The aircraft tire storage rack looks like the picture above. And not just tires, an airline will store many of the aircraft’s parts and these are closely managed by a separate department. They are responsible for purchasing, lending, repairing, exchanging components… for their own company or even another company if there is a request for cooperation.