Tire Wear On Heavy Widebody Jets ?

billt460

billt460

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Perhaps some of you guys like Astro can chime in here with some facts. I can't imagine what it costs to outfit, say a 747-400 with new rubber all the way around. It has to be staggering. Not to mention how many cubic feet of Nitrogen it takes to fill them.

And it's not like you can go to Discount or Big-O and get them mounted and balanced. Does extended taxiing induce a lot of wear? Say from the gate to the end of a 2 mile long runway? Or does the bulk of the wear come at touchdown?

I find it amazing there aren't more tire failures. Especially when they're slammed into the tarmac at 150+ MPH, with a touchdown weight upward of half a million pounds.
 
billt460 said:
Perhaps some of you guys like Astro can chime in here with some facts. I can't imagine what it costs to outfit, say a 747-400 with new rubber all the way around. It has to be staggering. Not to mention how many cubic feet of Nitrogen it takes to fill them.

And it's not like you can go to Discount or Big-O and get them mounted and balanced. Does extended taxiing induce a lot of wear? Say from the gate to the end of a 2 mile long runway? Or does the bulk of the wear come at touchdown?

I find it amazing there aren't more tire failures. Especially when they're slammed into the tarmac at 150+ MPH, with a touchdown weight upward of half a million pounds.
Click to expand...
90% of the wear occurs on landing, if I remember correctly tires are changed after so many of them or if they have "Hard Landings"
It's a safety item so they are pretty careful with this.
 
Heavy wide-body airplane tires are cool. Yes, they're always retreaded. They can be retreaded up to 7 times provided the carcass passes NDT and no damage is noted. Airplane retreads aren't like the 18-wheeler tires that leave the road gators all over the place.

Big, heavy airplanes have tires that are 32 ply and rated for 235 MPH. They wear out from landings and you usually only get a few months out of them before they're turned in for a fresh tread cap (we call them recapped and not retreaded). If you're lucky you might get 80 or 90 landings out of a tire before you have to call up discount tire direct and get a fresh set of skins. :)

Airplane wheels are two-piece, bolted together with a big O-ring in the middle to hold air, and they have little thermal plugs that will melt and provide a controlled deflation in the event of an overtemp. So they're not using a machine to spoon the tire on the wheel. They're placing the inner wheel into the opening and then the outer wheel with the O-ring goes in next. you push it together and clamp it down and off it goes. They're not balanced either. They shed so much rubber with each landing that a balance would be a waste of time.

And front tires are only slightly less robust with about 24 plies of reinforced rubber and also a nice 235 mph speed rating. Planes don't have brakes on the front wheels either so you don't have to worry about skidding the nose (unless you're JetBlue and you hire a second rate landing gear overhaul company).
 
billt460 said:
Perhaps some of you guys like Astro can chime in here with some facts. I can't imagine what it costs to outfit, say a 747-400 with new rubber all the way around. It has to be staggering. Not to mention how many cubic feet of Nitrogen it takes to fill them.

And it's not like you can go to Discount or Big-O and get them mounted and balanced. Does extended taxiing induce a lot of wear? Say from the gate to the end of a 2 mile long runway? Or does the bulk of the wear come at touchdown?

I find it amazing there aren't more tire failures. Especially when they're slammed into the tarmac at 150+ MPH, with a touchdown weight upward of half a million pounds.
Click to expand...
The tire are really heavy duty they do fail and remember Aircraft is a Latin word that means expensive. My neighbor owns a twin engine recip engine pressureized cabin plane and we talk planes and the ownership costs are unbelievable. I couldn't imagine the cost of an airliner. Then again I can not understand how the airlines stay in business.
 
Pelican said:
90% of the wear occurs on landing, if I remember correctly tires are changed after so many of them or if they have "Hard Landings"
It's a safety item so they are pretty careful with this.
Click to expand...
I am fairly sure the tires do not get much wear while in the air. I also very much doubt taxiing ads more than one or two percent to tire wear compared to those black streaks where the planes land.
 
I have never understood why they do not pre-spin tires. Maybe they don't want the weight and added complexity. You could spin then aerodynamically or with a small motor

Rod
 
No idea on cost, but a few years ago the 737s I fly switched from bias ply tires to radials. More expensive to buy, but lasts longer. Ultimately less labor to swap tires so cheaper overall.
 
Can you imagine the cost and wear on Navy jets during carrier landings, brutal. ;)
 
Pelican said:
Not a guess I worked for an airline!
Edited to add: I stand corrected Tom, they wen't allowed till I retired from it 24 yrs ago.
Now the FAA does accept them.
Click to expand...
It's an interesting topic. Bridgestone started retreading aircraft tires in 1953. Any aircraft you are in is most likely on retreaded tires. On Southwest, tires are replaced, with retreads every two or three months. Aircraft tires are designed with retreading in mind and can be retreaded seven (maybe more???) times. Be careful with this as it all came from a quick trip to Google.
 
Again what is great about BITOG is we have a varied range of industry professionals that can answer the questions as they are asked and I will say thank you all for sharing your knowledge.
 
TomYoung said:
It's an interesting topic. Bridgestone started retreading aircraft tires in 1953. Any aircraft you are in is most likely on retreaded tires. On Southwest, tires are replaced, with retreads every two or three months. Aircraft tires are designed with retreading in mind and can be retreaded seven (maybe more???) times. Be careful with this as it all came from a quick trip to Google.
Click to expand...
Possibly, but I know that the liability in case of an accident due to tire failure would have been crippling financially. Is it possible they were allowed on cago planes?
 
Decades ago a tire shop I worked one summer in high school was selling for agricultural applications recapped airliner tires which had failed inspection. Am guessing hay wagons or similar, I never saw one mounted.
 
ragtoplvr said:
I have never understood why they do not pre-spin tires. Maybe they don't want the weight and added complexity. You could spin then aerodynamically or with a small motor

Rod
Click to expand...
It can, and has been done, at least aerodynamically. Dont know that we will see it implemented on a commercial plane anytime soon, but it has been done.

My first job in aviation was tires (and brakes) for DC8 and DC9 cargo jets. I brought up pre-spinning even back then, thinking a few small, properly angled chines molded as part of the wheel assembly could likely produce substantial spin. The most I ever got out of it was a few raised eyebrows and a couple of eye rolls. But you dont know what you dont know, and you dont know what side of the Dunning-Kruger mountain your own brain resides on when you dream up stuff like this, so I kind of learned to keep my mouth shut when it came to voicing my brilliant, genius ideas.
 
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