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I imagine that the tires on commercial jets wear out pretty fast with all those squealing landings as the tire suddenly has to spin up from zero to the speed of landing.

2 questions:

How many landings does any average commercial airliner tire last before it is discarded?

Before landing, why not have a small motor assembly on the landing gear to spin up the tires to the correct speed? Surely this would avoid the degrading tire burn. The tire might last a lot longer and might even offset the cost of the motor assembly.

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  • $\begingroup$ This has been proposed many times and, I think, tried a few times through the years. Why it's not been adopted I don't know. Perhaps cost benefit? Would carrying the weight of a motor and it's maintenance cost negate the savings. What would be the savings? I seem to remember being told that the major wear of tires is not the spin up wear. Just as info, 747 tires were filled with pure nitrogen at 225psi as I recall. $\endgroup$
    – Terry
    Commented Jan 30, 2014 at 18:22
  • $\begingroup$ ... probably too many motors, to much added weight, invest and maintenance cost. Plus, a serious danger of skidding in case of a partial malfunction. $\endgroup$
    – yankeekilo
    Commented Jan 30, 2014 at 18:29
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    $\begingroup$ I've wondered why aircraft wheels don't simply have vanes on the wheels to spin them up when the gear are lowered. Commercial jets are going pretty fast on landing. $\endgroup$
    – Howard Miller
    Commented Feb 17, 2016 at 18:04
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    $\begingroup$ Related: aviation.stackexchange.com/questions/3702/… $\endgroup$
    – Peter Kämpf
    Commented Feb 17, 2016 at 22:48
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    $\begingroup$ @Terry: Spinning wheels add gyro effects. I guess lining up your 747 with the runway on final is much harder when the 18 spinning wheels add their roll-yaw-coupling. $\endgroup$
    – Peter Kämpf
    Commented Feb 17, 2016 at 22:52

3 Answers 3

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I've heard that airliners' tires will last about 200-250 depending on how many hard landings are made. Bizjet tires will last longer, and light aircraft tires will last indefinitely, depending on how gentle you are and what kind of surface you're landing on. I had one start cracking around the wall and just looking unsafe long before the treads ever started to wear.

As for the spin-up idea, it's been proposed many many times, but generally always rejected due to weight and maintenance costs. However, now that fuel is by far the main expense in an airliner's trip, companies are looking for any way to reduce fuel burn. As it turns out, taxiing an airliner burns quite a bit of fuel. They've already started turning one engine off for long taxis, and I think that electric wheel motors will be the next big thing.

The motors have gotten light enough and strong enough that they are a now a viable option. They can be powered by the APU or by a set of batteries (which are also now becoming light enough, see the 787 when they get the kinks worked out). So when they get around to putting them on aircraft for taxiing purposes, you can bet that they'll be spun-up right before landing.

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    $\begingroup$ Huh, we have several ultralights in our club, and let me tell those tires do age quickly (all preempted by your gentleness disclaimer, of course). $\endgroup$
    – yankeekilo
    Commented Jan 30, 2014 at 18:49
  • $\begingroup$ Related to your last paragraph: aviation.stackexchange.com/questions/956/… $\endgroup$
    – yankeekilo
    Commented Jan 30, 2014 at 18:51
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    $\begingroup$ @yankeekilo - I think it just depends on the type of tire, honestly. The tires I put on my plane are fairly thick and heavy, but they're meant to go on trainers and take a beating. I've never seen one wear down to the cords even though I do beat them up sometimes. But then look at the tires on, say, a Citation. They're not much bigger than those on a 172 but they handle many times the weight. I don't know how those last any time at all but apparently they do. $\endgroup$
    – StallSpin
    Commented Jan 30, 2014 at 18:55
  • $\begingroup$ Thanks. Yes, motors are now smaller and more powerful... you might even use them for regenerative braking after the landing... $\endgroup$
    – Arjun Khosla
    Commented Jan 31, 2014 at 5:01
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    $\begingroup$ @Arjun, the regenerated energy must be stored somewhere. Batteries? On board batteries are required for safety so landing with batteries low enough to accept the energy recouped from landing is counter to safety. You would need a heavy bank of batteries for this purpose alone. It does sound like a good idea but it is not practical with today's technology. $\endgroup$
    – Skip Miller
    Commented Feb 1, 2014 at 21:44
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Although tyres can wear out "pretty fast" with numerous landings however as long as the carcass is in good condition then the tyre will go for a retread rather than be discarded.

So from a purely economic point of view I suspect a retread is the cheapest option rather than trying to develop elaborate systems to extend the life of the tread. The other issues I can see with spin up motors is lack of space and temperatures. There is very little room inside a wheel rim for any motors, they are filled with multi-plate disc brakes. The brakes get very hot when braking and would be a very harsh environment for any motor. So far simpler and cheaper to retread the tyre when it starts to get worn out.

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This article would lend a number of roughly 240 landings per set of tires

an A340 will complete roughly 6,000 take-offs and landings, calling for about 25 sets of replacement tires

Since some aircraft tires can be remolded and to a large extent recycled they are a fairly decent part. In the end of the day the tires are sacrificial by design, its simply easier and cheaper to replace tires every 240 landings than maintain some complex spin up system or use some pricey material (which may or may not exist) that wears slower.

In response to this half of the question

Before landing, why not have a small motor assembly on the landing gear to spin up the tires to the correct speed? Surely this would avoid the degrading tire burn. The tire might last a lot longer and might even offset the cost of the motor assembly.

Take a look at this similar question but basically in short there are a few issues with pre spinning tires even if the system was viable from a weight standpoint. They did some research on it back in the day and found that pre spinning does not really reduce wear significantly (more on that in the linked answer).

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