# Flying with pumped up tyres?

#### dragon72

##### Guru
I've boxed up the bike ready for tomorrow's flight and realised that I haven't deflated the tyres as the airline says I should.
I have a vague recollection of a cycling science boffin hereabouts saying that it's a load of old cobblers about needing to deflate tyres for a plane journey.

So, can anybody tell me? If I leave my tyres pumped up in the box as they are right now, will I arrive at my destination alive and not having to go through the pumping rigmarole when I reassemble, or will the pressure in my pneus blow at 35,000 feet causing an aviation atrocity over the English Channel?

#### rualexander

##### Guru
I've boxed up the bike ready for tomorrow's flight and realised that I haven't deflated the tyres as the airline says I should.
I have a vague recollection of a cycling science boffin hereabouts saying that it's a load of old cobblers about needing to deflate tyres for a plane journey.

So, can anybody tell me? If I leave my tyres pumped up in the box as they are right now, will I arrive at my destination alive and not having to go through the pumping rigmarole when I reassemble, or will the pressure in my pneus blow at 35,000 feet causing an aviation atrocity over the English Channel?
It is indeed a load of old cobblers.
Even if your plane were to soar so high as to escape earth's atmosphere and the cargo hold was unpressurized, the difference in relative pressure between the inside of the tyre and the outside would only be around 14psi, something that most tyres would have no problem in containing.
In reality, the plane doesn't go that high, so the air pressure outside at cruising height is around 3psi, giving a difference of just 11psi from ground level. Also cargo holds are actually pressurized the same as the cabin (they often carry animals down there), at around 11psi, so that makes the difference only 3psi! A couple of strokes of your pump difference in fact. So nothing to worry about.
However, many airlines still insist on the tyres being deflated so if they ask to check your bike you will probably have to let them down, and if they ask you if you have deflated them you will either have to lie or own up!

#### rich p

##### ridiculous old lush
I didn't deflate mine last time but it was the oversized baggage handler who asked me if they were deflated not at the check-in. I lied!

p.s. When I say oversized, I mean the baggage not the handler!

#### betty swollocks

##### large member
Do they deflate the plane's tyres?
No.
It's cobblers.

#### Brains

##### Legendary Member
Whist as the 2nd post confirm it is indeed a load of old cobblers and totally not necessary, the issue is Airline Rules.
They are not permitted to fly with any pressurised containers, and a tyre is a pressurised container
So like it or not they types have to be at lest very soft, if not totally flat.

I'd guess the issue would be if there was a sudden 'BANG!!' in the hold at 20,000 ft as the staple of the box finally wore through your tyre, you would be as popular as a sausauge at a Kosher wedding when the plane has to make an unscheduled overnight stop in some fla ridden poxy air port in the middle of nowhere.

#### TheDoctor

##### Europe Endless
Moderator
There's no need whatsoever to deflate tyres, according to Ryanair.

Special advice for the carriage of bicycles
The pedals must be removed (or fixed inwards) and the handlebars must be fixed sideways. The bike MUST be contained in a protective box or bag. It is not necessary from a safety perspective to deflate typical tyres found on bikes and wheelchairs for carriage in the hold. However, to eliminate the small risk of them being damaged by bursting, you may wish to deflate the tyres.

Source

#### Brandane

##### Rain magnet.
Do they deflate the plane's tyres?
No.
It's cobblers.
Sorry to be an anorak , BUT..... to quote from Wikipedia "Aircraft tires are usually inflated with nitrogen or helium in order to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight."

#### GAVSTER

##### Well-Known Member
Sorry to be an anorak , BUT..... to quote from Wikipedia "Aircraft tires are usually inflated with nitrogen or helium in order to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight."

As air is 79 per cent nitrogen anyway - it appears a bit daft to fill completely with either Nitrogen or helium which is expensive and also leaks thru membranes more than air.

Interesting tho'

#### Alembicbassman

##### Confused.com
I worked on check-in at Heathrow for 3 years. We were always told to deflate tyres on bikes and wheelchairs.

Aircraft are pressurized to the equivalent of 8000 ft

So at 35000ft there's a 27000ft difference.

On a 747 bikes are usually loaded into Hold 5 which is heated (animals are also loaded here). The lower ambient pressure is going to result in an increased internal pressure in the tyre.

The other holds aren't heated so the tyres will have a lower pressure as the ambient temperature cools.

It's just a case of minimizing risk, just like when they tell you to turn off electronic devices on take-off and landing.

But if the crew hear a loud bang the aircraft may make an unscheduled landing to see what it was,and if they pulled out your bike with a floppy inner tube you'd feel a little silly.

#### ASC1951

##### Guru
...the pumping rigmarole when I reassemble...
I would hardly call pumping up both tyres 'a rigmarole'.

You need to take a track pump with you anyway, in case you get a puncture out there. I have a plastic jobbie which only weighs a couple of ounces more than my frame pump.

#### Globalti

##### Legendary Member
I worked on check-in at Heathrow for 3 years. We were always told to deflate tyres on bikes and wheelchairs.

Aircraft are pressurized to the equivalent of 8000 ft

So at 35000ft there's a 27000ft difference.

On a 747 bikes are usually loaded into Hold 5 which is heated (animals are also loaded here). The lower ambient pressure is going to result in an increased internal pressure in the tyre.

The other holds aren't heated so the tyres will have a lower pressure as the ambient temperature cools.

It's just a case of minimizing risk, just like when they tell you to turn off electronic devices on take-off and landing.

But if the crew hear a loud bang the aircraft may make an unscheduled landing to see what it was,and if they pulled out your bike with a floppy inner tube you'd feel a little silly.
Hell's teeth! So you actually believe that in the heated hold there's a greater risk of the tyre bursting? As somebody else mentioned, the difference is so small and as the entire fuselage of a plane is pressurised to 8,000-10,000 feet there is no likelihood of a tyre bursting. Do the tyres burst when the TDF goes over cols at 8,700 feet? No.

As for the sound of a bursting tyre causing the plane to make an emergency landing, have you heard the cacophany of horrible noises that Airbuses make when the flaps are moving or the wheels being raised or lowered? Do you think a passenger would hear a bust through the bike box, the luggage container and the floor and then report what they heard to the crew, especially if the plane was still flying in a straight line and their can of Carlsberg Euro-piss was still fizzing away on the tray? No.

#### Alembicbassman

##### Confused.com
The aviation business is risk averse.

Even if there is no absolute proof that something affects the aircraft they'll err on the side of caution.

If you are told to let your tyres down you either do it or don't fly. Simple as.

FlyBe terms of carriage for bikes:

Bicycles must be prepared as follows: Handlebars must be turned and locked in line with the frame, pedals must be removed or turned inwards, the front wheel must be removed and securely attached to the frame and the tyres must be fully deflated. The bicycle should then be bagged or boxed.

You can argue until you are blue in the face and appear on TV.

If you leave them pumped up the baggage handler may let them down or your bike may be loaded as is.

It may seem a stupid rule, but that's the business I worked in for 7 years (3 years check-in). It's full of odd rules.

#### frank9755

##### Cyclist
The issue is not so much the rules, which the quote from Ryanair illustrates, are often rational, it is what the chap standing between you and your flight home thinks the rules are, or should be.

Best advice is, obviously, not to deflate your tyres. Normally it is not a problem. If asked, 'have you deflated your tyres?' you can say 'yes, I have deflated my tyres'. You need not say that it may have been days, weeks or months beforehand. If the person then wants to check, you can say that you have let some of the air out - you normally run them at 120 and have deflated to 85 (or whatever). That normally works. I have never actually had to deflate.

#### TheDoctor

##### Europe Endless
Moderator
Personally, I'd take a Morph pump. In fact, the last time I put a bike on a plane, that's what I did.
End of the day, it's what some check-in muppet says, as frank points out above.
I am in a position to report that if a tyre blows out at 120 psi, it makes one helluva bang.
Happened to me on Sunday and I nearly jumped out of me lycra.
Nearly soiled it too!!

#### Alembicbassman

##### Confused.com
Anybody who gave us Check-in muppets a hard time used to get the crap seats next to the babies or in the middle of the row of 4 between 2 fat b*stards. So beware