In previous articles, we talked about how checking your tyre pressure and tread depth regularly can help to prevent your wheels from blowing out or aquaplaning. In this post, we’re going to dive a little deeper and discuss the average shelf life of a tyre.
Unsure what a DOT code is? Perfect – you’ve come to the right place! Read on to learn how to find a tyre’s manufacturing date, how long a tyre lasts on average, and what accelerates tyre deterioration.
How long do tyres last?
The consensus among tyre manufacturers and safety groups is that vehicle owners should replace their tyres roughly every 5-6 years. This is reiterated by the European Tyre and Rim Technical Organisation (ETRTO), which states that tyres may be considered new for 5 years from the date of manufacture. There are other sources, however, who suggest that the upper limit of operational life for a tyre is closer to 10 years, regardless of how much tyre tread is left.
We know what you’re thinking: 5 years is a lot different to 10 years, so why is there such disparity?
The truth is that no expert can accurately predict the lifespan of a tyre without firstly knowing more about how it is used day-to-day. For instance, if you regularly drive on incorrectly inflated tyres or expose them to rough road conditions, chances are that the tread will wear more quickly. Likewise, if you’ve picked up any bad driving habits or your wheels aren’t correctly aligned, this too could contribute to a shorter tyre lifespan. Other factors include how the tyre is stored, what sort of care is taken and the climate you drive in.
What’s more, tyres age according to a chemical process known as oxidisation. This is when the flexible parts of the tyre are exposed to oxygen particles, and the rubber begins to harden. Oxidisation happens whether a tyre is left on a shelf or it is used regularly; beginning from the moment it is manufactured – however, it accelerates at different rates depending on how the tyre is stored.
How to find and read tyre DOT codes
To the unsuspecting eye, all tyres look like same. But look a little closer and you will see that each one is embossed with its own unique set of tyre markings. One of these markings is referred to as a DOT code. You can think of this as a tyre’s birth certificate – an idiosyncratic stamp assigned to it from day…DOT (okay, we’ll stop).
The DOT code (an abbreviation for the US Government Department of Transportation) comprises an alphanumeric string of several characters – but it’s the final 4 digits that we’re interested in. Here’s how to read a DOT code:
- While there are many markings on a tyre’s sidewall, the DOT code is among the easiest to find because it begins with the letters “DOT”.
- The final four digits indicate the tyre’s production date e.g. 4419.
- The first two digits indicate the calendar week in which the tyre was produced. In this instance, 44. This is followed by the year of production – for example, 19, referring to 2019. (Prior to the year 2000, the date section of the code only had 3 digits, but this was later changed to clarify which decade the tyre was manufactured in).
- The letters and numbers that precede the DOT number are of less importance, but are useful for understanding a tyre’s manufacturing journey. In the first sequence of 4 characters (e.g. 2M1K], the two alphanumeric symbols represent the plant code, or where the tyre was manufactured. In this example, 2M refers to Bridgestone/Firestone North American Tire in Bloomington, Illinois. The third and fourth characters refer to the tyre size code.
While DOT codes are used primarily to track tyres in the event of a product recall, they are handy for predicting the shelf life of a tyre, not least if you have lost your receipts. Remember, the age of your tyre starts from the manufactured date, not from the period you have it fitted.
TOTD top tip:
“Remember to check the DOT number on your spare tyre, too; especially if you’ve never replaced them.”
How old is too old?
As a rule of thumb, you should use your tyre’s production date in conjunction with the technical condition of your tyre when deciding if a replacement is required – as opposed to in isolation.
If, for instance, your tread depth falls below 2mm but your tyre is less than 5 years old, it doesn’t mean you should forgo a replacement. On the contrary, any significant loss in tread depth should be treated seriously, as should any other physical defects (cracking, bulging, etc.).
Likewise, even if a tyre looks physically sound, it still might not be suitable to drive on – especially if it hasn’t been stored correctly. The components inside a tyre aren’t indestructible and could separate for any number of reasons without showing any external damage.
When in doubt, you should heed the advice of tyre expert Daniel Bezer:
“Tyres are designed and manufactured to give long service under typical operating conditions. For most tyres, a replacement will ultimately be triggered by tread wear. However, adverse environmental, operational or storage conditions can make it a replacement tyre necessary before the tread is worn to the legal limit.
Tyres should be inspected at least monthly and attention should be paid to tyres that are used infrequently. Some tyre and vehicle manufacturers make recommendations regarding the maximum age of tyres in use. This guidance should always be respected.”
Think your tyres are too old?
Don’t wait for your MOT to fail or an accident to arise. Get in touch with our customer support team by calling 0333 016 6550 and we’ll send one of our brilliant tyre technicians out to fit a suitable replacement.
That’s right. No trips to the garage. No need to cancel your plans. No need to wait. Tyres On The Drive put you firmly in the driver’s seat.