When we buy new car tyres, we like to use them for as long as possible. Because of this, we often ask the seller how many seasons or miles a given tyer will last. Unfortunately, such an answer is never easy, as there a multitude of factors that can contribute to this.
This article serves to help more accurately answer this question, looking at the various factors that do contribute to a tyre’s lifespan. Yet, one should never forget that both tyre design and tyre construction are constantly improving. Consider the following:
On the 11th of June, 1895, in a Paris-Bordeaux-Paris race, a car was first used with pneumatic tyres. Edouard Michelin finished ninth, driving a Peugeot with 4 HP, developing a top speed of 16 metres per second. To cover the total distance of 750 miles, he had to change tyres every 33 miles. Today, tyres are replaced almost 1000 times less frequently.
So, when should you change your tyres? This decision to swap out old, worn tyres for new ones can be influenced by the following major criteria:
Individual preferences of the driver
We have previously discussed the issue of a tyre’s technical condition, which can sometimes indicate a need to replace the tyres earlier than expected. This time, we will focus on the age and the tread wear factors.
How often should tyres be replaced?
In the UK, as well as most of Europe, the legal tread depth for summer tyres if 1.6mm. This is the length that must be present between the height of the wear bars and the level of the tread wear index (TWI).
The thickenings in the grooves, situated at several places on the tyre perimeter, are the wear indicators. They are found on the borderline between the tread and the side of the tyre.
An example of a wear indicator on Michelin tyres.
A wear indicator in the form of a triangle.
If a tyre reaches such a wear level, it should be replaced immediately, as its further use is illegal. In the case of a roadside inspection, the driver can be fined and the police may even retain the vehicle registration certificate.
In the case of a collision, it will be extremely difficult to get compensation from the insurer, regardless of whether or not the collision was your fault.
Furthermore, with the tread worn down to the TWI, such accidents are more likely. Numerous tests and studies have shown that a tread depth of 3-4 mm affects the tyre’s performance on wet roads, especially as as a strong resistance to aquaplaning is concerned. This, naturally, only worsens the closer to the tread wears down to 1.6mm.
How many miles can You drive on summer tyres?
This depends how much you drive every year. With an average mileage of around 30,000 miles a year, tyres may need to replaced on a yearly basis. However, how many miles a tyre will ultimately last depends on a large range of factors, including:
The wear resistance of the tyre, including the compound, tread pattern and structure.
Your driving style.
The types of routes (such as city, motorway or rural roads) that you take.
The types of surfaces, with particular focus to the coarseness level, that you encounter.
The tyre pressure level.
The load index and weight of your car
Your driving speed
This is just a few of the factors, as the whole list is rather extensive.
A tyre used to the TWI level.
Because of this, it will always be difficult to talk about average values of wear resistance. However, an analysis of wear resistance shows that they are characterized by normal distribution. The largest number of drivers, operating in a moderate manner, reach a range of 15,000 to 30,000 miles with their tyres.
Average tyre mileage in Europe.
How often should winter tyres be replaced?
The compounds used in winter tyres are usually characterised by a lower wear resistance than summer variants. As a result, the mileage from a winter model can often be 15-30% shorter than traditional summer tyres. This distance can be shortened even further if such tyres are used at temperatures higher than 10 degrees Celsius.
Indicators: TWI and winter index and their markings.
How often should all-season tyres be replaced?
When it comes to all-season tyres, these should be treated similarly to winter tyres, as far as the tread depth is concerned. This is especially important when you consider that, in the majority of all-year tyres, the winter properties are lower than those found in dedicated winter tyres.
As far as durability is concerned, all-season tyres sit somewhere between summer and winter options. In addition to being more suited for summer driving, they will often show their advantage over winter tyres during autumn and spring. From an economic point of view, it is unwise to use winter tyres outside of winter, due to the excessive wear that will occur.
TWI and winter markings on an all-season tyre.
However, this is specifically referring to all-season tyres designed for the European market. Alternatives designed for American markets, or even cheap models provided by Chinese tyre companies, are sometimes characterised with an above-average wear resistance. Yet, it should be noted that this is achieved at the expense of their safety parameters and these tyres rarely comply with European road requirements.
Regarding the age criterion, it is often said that tyres should not be used for longer than 10 years after the manufacturing date, even if the tread depth is in line with legal regulations and the tyre bears no visible signs of ageing.
Does this mean that all tyres older than 10 years cannot be used? No, but it should be noted that they are definitely less safe. With time, the tread compound, as well as other components of the tyre construction, lose their properties. This results in a tyre that does not ensure grip, braking or steering as well as a ‘fresh’ new equivalent.
Furthermore, the wear and tear, as well as other undesirable processes, such as the progressive corrosion of the steel belt via water penetration, makes such tyres more susceptible to various kinds of damage and failure.
So, if a tyre has a 3-digit marking on the manufacturing date, we should think about replacing them. Additional, it is often recommended that tyres should be inspected regularly by a specialist after their 5th year of use. As far as winter tyres are concerned, due to their increased wear, drivers should highly consider replacing them when they are 5 years past their manufacturing date.
Tyres are also subject to ageing when they are not in use. This happens in two common situations:
Tyres are installed on a car which is not in use, becoming deformed when a car is parked for a long time.
The tyres are not correctly stored in appropriate conditions. Tyre storage requirements are quite specific and must be adhered to if you want to ensure their lifespan.
This is something to consider for all of your car tyres, while many people will actively take this into consideration when purchasing new tyres. When you know, approximately, how long your tyres will last, you can make better decisions in terms of tyre value, wear resistance and general use.