MIAMI — Have you ever wondered how often an airplane gets its tires changed? How about the weight, pressure, or even the size of these tires?
These rubbers need to support a 500,000-pound jet coming down hard without blowing up or tearing apart. In fact, regulations demand that airplane tires must withstand up to four times their rated pressure for as long as three seconds.
Made of basically the same materials as car tires, the main difference these super large tires have is that they are blown up to about 200 psi—almost six times more than what regular car tires can withstand.
Also, these super strong rubbers are reinforced with cords of nylon or a synthetic polymer called aramid—all of which are tightly embedded under the tire’s tread.
A Boeing 777 uses 12
Each tire is worth about $5,000.
To put things into perspective, Emirates, the world’s largest Boeing 777 operator with 163 of them in service, needs 1,956 tires and 1,956 spares to keep its Triple-Seven fleet’s main landing gear operational.
Alitalia, with 11 Boeing 777-200(ER)s and one 777-300(ER), needs about 288 main landing gear tires. About $1.4 million worth of rubber in stock!
The Italian flag carrier eloquently produced a video, in partnership with Airways Staff Photographer, Fabio Sorce, demonstrating how the 777-300(ER)’s tires are changed in a one-minute time lapse.
Video: Changing Tires On a 777-300(ER) in One Minute
“Airplanes also need to replace their tires, just like cars,” says Alitalia. “The difference is, basically, in its measures. Check out a one-minute time-lapse of a pit stop of the flagship of our fleet, the Boeing 777-300ER.”
The Solution To An Expensive Problem?
Tire wear is one of the biggest cost items in airline maintenance. A study published by Embry-Riddle Aeronautical University suggests that 99% of tire wear “could be eliminated by pre-spinning the tires prior to touchdown,” which would eliminate the one-sided impact that the tire suffers when touching the ground at high weight and speeds.
“The impact an aircraft has on its tires when it lands has been problematic practically since the invention of the airplane,” says the study.
“Upon touchdown, the tires frequently smoke as rubber burns off and tire material is worn away while the tires slip up to a steady rolling speed. To minimize tire slip, torque or spin mechanisms could be added to each tire assembly to accelerate the tire to match the landing speed.”
“In this paper, a case study is presented of a Boeing 747-400 aircraft touching down on a runway and its wheels spinning up to match the forward speed of the aircraft as it rolls along the runway,” says Embry Riddle.
“We conclude that the amount of rubber worn from the tire on each landing is proportional to the kinetic energy that the wheel must gain to reach a free-rolling velocity. Therefore tire wear is proportional to the square of the initial difference between wheel speed and horizontal aircraft velocity.”
Today, most of the wear and tear to a plane’s tires happens during initial touchdown.
It is estimated that an airplane tire lasts as long as 500 touch downs before they need to be replaced or re-tread.
If the damage is not substantial, a tire can be put back into service up to seven times over the course of its useable life, according to Popular Mechanics.