Why do you deflate tires on a plane?

I don’t. Tires can handle 8 bar, I pump them to 4,5-5 bar, pressure difference between ambient and up in the sky is at most a little over 1 bar. Luggage btw compartment is [pressurized].(airliner - Are cargo holds pressurised these days? - Aviation Stack Exchange)

So why?

I don’t, It takes an outrageous amount of pressure to blow a tire off the rim and the pressurized cabin/cargo hold on an aircraft is pressurized to around 10.9 psi ambient ~8000’ if going from sea level to 8000’ was an issue my tires would explode every time I ride up Mount Lemmon.

The reason given when I last flew with a bike was that the luggage hold wasn’t pressurized, so the differential might be too much. This was back in the 90s and we all had 20c tires pumped up to the maximum we could achieve with our cheap plastic zefal frame pumps (so probably not much more than 60psi in reality, if we’re honest…). I do seem to recall a story of at least one blowout.

You probably don’t need to deflate them all the way, but at the same time I wouldn’t bother pumping up to race pressure before disassembly. Other than worries about a tubeless tire coming off the bead, I can’t see any disadvantage to doing it, so why not?

The baggage compartments have always been pressurized, so not sure whet the recommendation to deflate came from.

(The cylindrical fuselage makes an excellent pressure vessel, so it’s far easier to pressurize the full thing than to separate it with a flat floor.)

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I should have explained that that was what we were told, not necessarily that it was true at the time.

Had this conversation awhile back regarding deflating suspension… Regardless of whether they are or are not pressurized (they are) there isn’t enough of a differential to cause an issue, and what differential there is is offset by the temperature drop since most cargo areas are not heated(air density increases at lower temperature, bringing pressure down). Can’t remember the exact numbers but a plane flying at 40,000 feet only has something like a 12-15psi differential compared to at sea level so unless you’re running maxed out pressures and the cargo area happens to be heated you wouldn’t have a problem.

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I do, only because I can’t get my wheels with tyres inflated fitted into the designated space for them in my bikeboxalan. If I didn’t have to I wouldn’t, for the reasons stated above.

Someone somewhere will have overinflated a tyre that’s burst. Airlines take a strict line of safety - as they should. They don’t make rules by “yeah it should be ok my tyres can handle it”. They will use an abundance of caution, which is prudent. Just deflate them it doesn’t hurt, unless it’s tubeless!

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