Why do lorries leave their back doors open when they park in a lay-by overnight?

Take any trip down a major road late at night, and you'll invariably see lorries parked overnight with their rear doors open.

Why is this?

Many people think it's to show prospective thieves that there's nothing worth stealing; others say this is to show the authorities that they are not carrying illegal immigrants.

Both theories are wrong, and the truth is all about SCIENCE.

As the sun comes up in the morning, the air inside the truck body expands. All well and good in normal situations, but in something the size of a 40 tonne truck, this could be disastrous. Sun up, air expands, and BOOMPH, Eddie Stobart exploding all over the place. All truck drivers know this life-saving fact, and now you do as well.

Thanks to hard-working and safety-conscious truckers, we haven't had a Dawn HGV Explosion Anomaly since 1973.

Well done lads (and lasses). Have a Yorkie.

NINJA EDIT --- Ben on that there Facebook says: "That's why they put air holes in those boxes for carrying pets to the vet in. It's not so the little critters can breathe..."

Wow.