There has been some discussion and confusion over whether tyres do expire. This can lead to mismatch expectations when purchasing a new set of tyres. Does tyre, seemingly a hardy product, have an expiration date? We explore this question and the guidelines issued by manufacturers.
So, Do Tyres Expire?
While there is a manufactured date, there is no official expiration date for tyres. Tyres do not expire like how you would imagine food expires. That said, there are guidelines on using aged tyres. But first, we must state categorically that tyres do degrade over a long period of time and below we breakdown the factors causing degradation.
Aging Factors
The main cause of tyre degradation is oxygen or commonly termed as oxidation. Oxygen coming into contact with tyre will break down its rubber material properties causing dryness and making it brittle. The rubber is supposed to be flexible as it rolls under weight. In extreme cases, aged rubber is susceptible to cracks and/or causing the tyre to delminate (tyre belt separation). This would compromise the tyre’s functionality. To slow down the oxidation process, antioxidant compounds are used during the manufacturing process.
Heat is another factor that affects oxidation rate. When tyres are stored under high temperature, it accelerates the oxidation process and reduces storage lifespan. Therefore proper storage can extend a tyre’s shelf life.
Tyres exposed to sunlight will absorb UV radiation which breaks down the chemical in the rubber materials. However, manufacturers combat this problem by introducing carbon black that will absorb the UV radiation, which converts it into heat for dissipation.
Ozone, or ozonolysis, is another factor that can degrade tyres by causing the rubber’s polymer chains to break down. Ozone is essentially oxygen but with an extra atom reacting with rubber. But just as with UV radiation, manufacturers overcome this problem by applying physical or chemical antiozonants to prevent ozonolysis.
Manufacture Date
Now we are aware that tyres do degrade over time, it is useful to first determine a tyre’s manufactured date, which will give us a sense of the tyre’s age. This is represented by DOT, which is made up of a few characters and followed by 4 numbers at the end. These last 4 numbers represents the manufactured date.
The first 2 numbers represent the week number and the last 2 numbers represent the year. For instance, in the example above, the last four numbers are 2720. This simply means the tyre was manufactured on the 27th week of 2020 or around June/July of 2020.
Guidelines
Although tyres do degrade over time, it is not an overnight process. Technological advancements have improved the manufacturing process that slows down tyre aging. In fact, it is more likely the tyre tread will wear out first before tyre degradation occurs catastrophically.
Back in 2017, Michelin Malaysia published a report on using aged tyres. They found that “tyres degrade 20x more rapidly when used verses those kept in storage”. Also in Korea, the Korean Department of Customer Protection found that tyre wear between new tyres and 3 year old tyres were identical. Finally Michelin reported that in Germany, the German motorist organization found that rolling resistance was also identical between new tyres and 3 year old tyres.
Extracted from Michelin Malaysia Report
Now that we clarified that tyres do not expire, we want to highlight the guidelines on using aged tyres. However, take note that guidelines differ between countries and regions. For instance, some states in the USA advise that tyres can be stored up to 6 years while another state may advise storage of up to 5 years.
The guideline in Singapore is that tyres are fit for use within 5 years from their manufactured date. This is also inline with the average warranty period of 5 years from manufacture date provided by tyre manufacturers.
Tyre Aging Signs
It is good to be aware of tyre aging by doing a visual check on the tyre. The main sign of tyre aging is when you notice cracks on the tyre. Aging factors such as oxidation causing the rubber to breakdown will result in separation of tyre causing cracks to appear. Cracks may appear on the sidewall of the tyre or in between the tread. So do a visual check during purchase of new tyres or if your current tyres are past the 5 year mark.
Recommendation
As a tyre ages, the rubber will harden over time and cracks tend to appear. This affects the grip and handling of a vehicle especially when you travel for extended distances. For instance it is not recommended to drive across states in Malaysia that may cover hundreds of kilometers using expired tyres. Thus if you do long distance travelling, it would be prudent to ensure your tyres are within expiration guidelines or certified safe for use by a tyre technician.
In Singapore, the guideline is that a tyre’s expiration date is about 5 years from their manufactured date. Thus upon new tyre installation, it would be optimal to have a balance timeline that lasts your average usage time frame.
For example, suppose a driver typically uses up a tyre’s tread within 2 years. It would be acceptable to install a new set of tyres that is 3 years old as you would have a balance of 2 years before the 5 year period.
Michelin Malaysia also came to a same conclusion. And this was not based on their own testing but independent tests results from Korea and Germany – research shows that performance is identical between new tyres and tyres produced 3 years ago.
Extracted from Michelin Malaysia
Naturally these recommendations are contingent upon the tyres being in good condition. On the other hand, one does not need to be fearful that tyres stored for between one to three years are “expired” goods. Under proper storage conditions, these tyres are considered equivalent to new tyres.
Does that mean that tyres past 5 years old should be replaced? It depends on the condition of the tyres and the usage pattern. Look out for signs of aging on the tyres. Drivers can also take note of tyre care to prolong the life of their tyres. For instance, if a vehicle needs to be parked for an extended period of time, it would be good to park the car under shade or to use a cover to limit exposure to sunlight and heat. For peace of mind, tyres that are past their 5 years mark should be brought to a tyre technician for inspection. However, for tyres that are past 10 years old, they should be replaced regardless of their condition.
Summary
- Tyres are fit for use within 5 years period of their manufactured date
- Look out for extensive cracking on the tyre, which are signs of tyre aging
- Tyres past their 5 year mark should be inspected by a tyre technician for roadworthness
- Tyres past their 10 year mark should be replaced regardless of their condition