Tyres get old too

Practical Motoring Says

Tyres should be replaced when:

  • their tread wears down to the legal minimum at any point across the breadth.
  • The minimum is 1.5mm although off road tyres should be replaced at 2/3 of their tread depth as 1.5mm on a deep-tread mud or all terrain is not a joke, it’s dangerous;
  • there is significant damage, for example anything which exposes the underlying carcass or canvas, or bulges indicating internal damage;
  • there is legally irreparable damage, for example a sidewall rip
  • they become too old

It’s this last point about age that’s not well known, and it’s a problem for trailers which tend to do very few kilometers so tyres come up for replacement by age, whereas cars tend to do enough kilometers to replace by wear. Even worse, all tyres lose air over time and trailers generally aren’t serviced very often so they often run under-inflated, or correctly inflated for no load, but under-inflated when loaded.

All tyres have a DOT manufacture date code of four digits. It looks like this:

Dot age

The format is week, year of manufacture, so 3916 is the 39th week of 2016, or September  2016. Some older tyres may have a single digit for year, for example 328 would be the 32nd week of 2008.

The DOT manufacture date may be only on one side of the tyre, so if you don’t see it on one side, look on the other. There are other DOT codes to do with the plant the tyre was made at, but it’s the age we’re interested in.

Now you know the age of your tyre – how old is too old?

Rule of thumb is 5 to 7 years and definitely under 10, on a caravan it will still have stacks of tread left but it should be replaced to maintain safety. 

You know a tyre is definitely too old or damaged when there’s stress fracture marks across it, but even before that time it won’t be performing at its best. And when those cracks form, they do so on the inside of the tyre so you can’t see them.

NB if you are at all unsure you are able to complete this check  then take your van to the nearest tyre  business and have them do a thorough check