Warning Triangle
A warning triangle has no fixed expiry and often lasts well over 10 years — but it must be replaced once the reflective strips crack, peel or fade, because a dull triangle cannot do its one job.
No printed expiry
Unlike a smoke alarm or a car seat, a warning triangle carries no printed expiry date and no legal replacement interval. A good triangle built to ECE R27 can sit in the boot for well over a decade and still do its job. Its life is measured not in years but in condition — the moment it stops being bright and rigid, it stops being useful.
What actually fails
Two things age. The reflective and fluorescent strips dull under UV light and lift at the edges, so the triangle no longer catches headlights from 100 metres away; and the plastic frame and hinges grow brittle, so legs crack or refuse to lock. A triangle that will not stand straight in wind, or whose red has faded to pink, is replaced — cheaply, and long before it fails you on a hard shoulder.
In the car
In Germany a warning triangle is compulsory in every car, and after a breakdown it is placed about 100 metres back on a motorway, well before the vehicle. Store it flat where it will not be crushed under heavy loads, and check it whenever you check the first-aid kit — the two ages tend to run together.