I was checking the regulations for flying with my bike, and it says to make sure the tyres are inflated.
Surely that should read "Not inflated"? wouldn't the air pressure blow them if they were inflated?

There was some discussion about this recently, the consensus was to leave them inflated.

Hi you do not need to deflate the tires as the cargo hold is pressurized

Thanks for that, much appreciated. It clears it up for me.

+1 to cdstg. The lower deck is part of the aircraft's pressure vessel. Otherwise, liquids in checked baggage would freeeze, cans of shaving cream would explode and never mind what would happen to pets that are carried down there.

No, you don't need to deflate the tires to take the bike on a plane. Atmospheric pressure at sea level is 14.7 psi, so even if the tires were placed in a complete vacuum the effect would be no worse than over inflating them by 14-15 psi. If that's all it takes to blow your tires, something's wrong.

+1 to DSchlichting, except I think liquids in checked baggage might vaporize before they froze unless they were tightly sealed. How can we test this?

When I flew to Italy last May with Lufthansa they made me deflate the tires on my bike for both flights, there and back. When I got back I e-mailed them with a complaint about how unnecessary this was, and what a drag it was to pump up 26 x 1.75 tires with a hand pump after a sleepless overnight flight in the worst seat on the plane. I got a phone call from a very nice customer service lady who discussed the issue with me and promised to research the matter. A few days later I got an e-mail from Lufthansa saying that I was right, and they were going to change the rules so people didn't have to deflate their bike tires. Lots of applause to Lufthansa for listening to their customers!

On all the flights I've been on they've mentioned deflating my tires, but I think I've forgotten just about every time I've flown with my bicycle, and it has not been a problem.

I think baggage is only partially presurized, perhaps it depends on the plane. Pets do occasionally suffer a stress greater than they would in the cabin, which is partially pressurized to the extent that ears sometimes pop. Not that any of that changes much.

Please let the air out of your tires. It is not an issue of physics, it is an issue of a false alarm. It is also a rule, a regulation, and just good sense. Bicycle tires do periodically blow out and it sounds like a gun shot. Do you want to be responsible for having an airport cleared for security reasons when a "gun shot" goes off while you are checking in for your flight? Flights will get delayed and you won't be a real popular person that day. Cyclists are responsible people and should observe the rules. It isn't that much effort to pump up your tires at the end of the trip. Be a responsible traveler.

If you understand the physics, then the rest is just, well, silly.

You don't work for Homeland Security, by any chance, do you? Your sense of hyperbole could be put to good use over there.

I don't really know why airlines insist on the tires being deflated. All I know is that if they are not, baggage handlers crack the valve, and then you can't re-inflate them once you get to the airport. This happened to me at Gatwick.

Commercial jets are pressurized so that the cabin and baggage area pressure is equivalent to 10,000' altitude when the jet is cruising above 30,000' At that pressure altitude, the ambient pressure if about half of what it would be at sea level, so the pressure differential between your tire and the ambient air is only increased by 7 or 8 psi. (That's a rough guestimate, it's been a while since ground school)

This pressure altitude is equivalent to taking your bike to the top of Haleakala on Maui. How many riders would deflate their tires for that ride?

Hi folks. I don't work for Home Land Security. Although, I don't understand why there is so much effort to bend the rules. I haven't hurt myself in any trip by inflating my tires when I arrive at the other end. Life is made up many times of making a choice of mistakes, small ones vs. large ones. I see it as a small mistake to abide by the rules and get a little pumping exercise. Signing off while everyone else jousts with the windmills.