Tyres and microplastic pollution: what's the problem and what’s being done to address it?

What is microplastic pollution?

Previous research from the USA has estimated that 30% of the microplastics that are polluting Earth's oceans and waterways comes from tyres.

Other research done in Germany in 2018 found that microplastics from tyres and vehicle brake pads made up 89% of the particles taken from the air above motorways. The scientists believe these tiny particles are being blown by the wind and washed by rain into waterways that lead to oceans.

What’s is the government doing about the problem?

In the wake of a number of recent studies of microplastic pollution in the world’s oceans and the air above busy motorways, the UK government commissioned research into the issue in May 2018. The results from this 11-month project, conducted by Plymouth University, are due soon.

The Department for Food and Rural Affairs (DEFRA) pledged £200,000 to pay for the research, which will analyse how tiny plastic particles from tyres and other synthetic materials, such as polyester from fishing nets, ropes and lines, enter our waterways and oceans and the impact they have on marine life.

Environment minister Thérèse Coffey commented on the DEFRA-funded research: “The impact of plastic pollution on our oceans is one of the greatest environmental challenges of our generation. Robust scientific evidence should support our policy proposals, and through this exciting project, we will build on work under way to better understand how microplastics end up in marine environment and what we can do to tackle this in the future.”

What are the tyre manufacturers doing about the problem?

Tyre makers refute the claims made from previous research. Eleven of the world’s leading tyre makers formed a global forum in 2005 to look at issues relating to tyre particulates. The Tyre Industry Project (TIP) aims to proactively identify and address the potential human health and environmental impacts associated with tyres.

According to a spokeswoman from Continental Tyres, which is also a member of the TIP, the microplastics from roads consist of 50% of material from tyres and 50% of material from the actual road surface. She stated that contrary to other research, the German company's initial investigations show that only 2% of tyre microplastics have the potential to get into oceans, because they're heavier than water so sink to the bottom of rivers rather than make it to the ocean. TIP is continuing its research and expects to publish findings in 2020.

Which are the best tyre brands and how can you save money on tyres?

You probably don’t give your car’s tyres much thought until a garage tells you they need replacing, but they're one of the most important safety items on your car. They provide the only contact between your car and the road and ensure that it makes it around each corner and stops when you want it to. 

In fact, every manoeuvre you make in your car relies on the tyres, so it’s vital to ensure they are in first-rate condition and that when you replace them, you do so wisely.

When should you replace tyres?

Although the legal limit for tyre tread depth is 1.6mm, many safety organisations and tyre makers recommend replacing tyres when the tread reaches 3mm, because their effectiveness – in particular their ability to stop a car on a wet surface – is reduced once the tread is below this level. They must also have the minimum tread across three-quarters of their width without any gaps.

The other legal requirements for tyres are that they are in physically good condition – they can’t have any gashes or bulges in the sidewalls – and are inflated to the recommended pressures. The tyres also have to be the same size across both axles, although you can fit larger tyres on the back or front axle of your car. 

Break any of these rules and you could get three penalty points on your licence and a £2500 fine. You could lose your licence altogether and be fined £10,000 if all four tyres are below the legal limit.

Although there’s no legal requirement to stick with the brand of tyre fitted to your car when it was new, the car's maker will have worked closely with the tyre company during development, so changing to a different brand or tyre with a different tread pattern could affect the handling and road noise. However, if you stick with a similar tyre from a different premium or mid-range brand, the differences should be minimal.  

One thing you should consider doing, however, is changing the two front or rear tyres at the same time, unless you’re replacing a new tyre that’s been damaged. If you change a single tyre and the new one has 8mm of tread and the one on the other side has 4mm, they won’t provide the same grip. While this isn’t likely to be an issue on dry roads, stopping distances will increase in wet and wintry conditions. 

You might be able to save money by looking for retailers that offer a discount for buying more than one tyre.

Should you fit new tyres on the front or back?

Most modern cars are front-wheel-drive, so the front tyres have to work harder than the rears and are likely to wear out quicker. However, whether your car is front, rear or four-wheel drive, most safety experts advise switching the tyres around when replacing the front pair so that the new ones are on the rear. 

This is because if a car loses grip in a corner, it will either understeer or oversteer. Understeer is when the car’s front tyres lose grip first, making the front end slide outwards. Oversteer is when the rear tyres lose grip first, making the back end of the car swing out. 

It’s easier to get a car that’s understeering back under control than one that’s oversteering – simply slowing down should help to regain grip – and this is why the new tyres should be on the rear wheels to minimise the potential to oversteer and risk a serious accident.

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