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Understanding the Role of Tyre Tread Depth on Car Safety

Most drivers will follow their car’s maintenance schedule strictly to ensure it’s at the top of its game. However, most of the service activities are focused on the vehicle’s power train. Whilst this is important, neglecting your tyres can have drastic consequences for safety and efficiency and can even leave you in a difficult legal situation.

Car tyres are important as they keep you and other road users safe. Complying with the minimum tyre tread depth the UK has established is a simple but effective way of keeping you safe and out of harm’s way.

The Importance of Tyres

legal minimum tread depth

The three basic functions of the tyre are to carry, guide, and transmit. It carries the load coming from the weight of the vehicle along with any aerodynamic overloads while absorbing the irregularities in the road at the same time.

Each time you turn a wheel or push the brake pedal, it causes a change in your vehicle’s trajectory or speed. It guides the vehicle in the path decided by drivers, and it transmits the acceleration or braking force decided by the driver. The tyres are the most important part when it comes to safety and also the most actively used safety equipment for your car. 

The tyre tread depth affects car handling and provides grip with the road surface. You’ll have a better grip with a deeper tread. The minimum tyre tread the UK imposes on vehicle owners underscores the government’s concern for the safety of passengers. 

The Role of Tyre Treads

worn tyres

Tyres are the only point of contact between your vehicle and the road. They make possible steering, braking, and transmitting power. The tread depth of tyre plays a crucial role in maintaining the safety of your vehicle when these activities are carried out. It affects car handling and provides grip on the road surface   

New tyres have a tread depth of 8-9mm. You can safely drive until your tyre’s minimum depth of the tread measures 1.6 mm, across 75% of the tyre’s width and all around its circumference. Safe driving in wet and snowy weather conditions is affected to the greatest extent by the car tyre tread depth. Tread pattern design and the rubber compound of the tread of your tyres are also contributing factors. Lower tyre tread depths will cause a progressive decline in braking performance on wet and snow-covered roads.  

Checking Your Tyres’ Tread Depth

minimum legal tread depth

Check your car tyre tread depth every 14 days, ideally before every long journey. First, check out the tread wear indicators. These are small horizontal bars that are evenly spaced and built into the grooves of your tyres around their entire circumference. Remember that the minimum tread depth requirement in the UK is 1.6 mm. This should be your basis for deciding when your tyres need replacement. Once your tyre has worn level with these tread wear indicator bars, you have reached your minimum tread depth. Your tyre will need replacing.

The 20p Test

20p tyre test

As per the above image from – Insert a 20p coin into your tyre’s main tread grooves. If you can’t see the coin’s outer band, your tread is above the legal limit. If visible, consult a tyre expert immediately. For accuracy, check three spots on each tyre. Use the 20p test to quickly assess tread depth.

Tyre gauges are a more accurate way of tyre depth measurement. Some gauges come as laminated cards with colour indicators and there are digital tyre depth gauges.

Simply insert the gauge into the tyre’s groove and you’ll know how close you are to reaching your minimum depth.

When are New Tyres Needed?

car tyre begins life

There are a few aspects to consider when deciding to replace tyres, including the following:

Wear and Tear

Too low car tyre pressure accelerates the wear of car tyres. It also results in higher fuel consumption of up to half a litre per 100 kilometres.

Uneven wear is another indicator that new tyres are needed. In some cases, much of the tyre has sufficient tread depth while other parts do not. There could be different tread wear indicators and reasons for this condition such as:

  • Tyres not running parallel to the direction of travel

  • Incorrectly set tracking 

  • Static or dynamic imbalance on the tyre

  • Bumping the curb when parking  

  • Faulty shock absorbers or a wheel bearing with too much play         

Tread Depth of Tyre

The legal tyre tread depth is 1.6 millimetres minimum. For optimal performance, some tyre experts recommend at least 3 millimetres for summer tyres and 4 millimetres for winter tyres.

Age of Tyres

A few tyre manufacturers generally advise that tyres are replaced after ten years at the very most. Others go for five or six years at the most. After only a few years, tyres no longer possess state-of-the-art attributes. The rubber compound hardens over time causing the materials to suffer from fatigue and becomes brittle.       

Tips on Tyre Care: How to Maximise Using Your Tyres

tyre tread depth gauge

Thinking of ways to use your tyres as long as you possibly could? Here are a few tips to keep in mind:

1. Check your tyres against irregularities.

Always check your tyres against abnormal wear and tear and other irregularities like worn tyres, embedded foreign objects such as nails, cracks due to puncturing or cutting, and bumps on the outer walls. Do this, especially before leaving on a long journey.   

2. Check your tyre tread depth.

Safety should be the overarching priority. Tyre depth should be the most important factor to consider even when thinking of ways to maximise the use of your tyres. It always pays to follow the legal tyre tread depth the UK recommends.

3. Check tyre pressure regularly.

Low pressure increases wear and tear and results in higher fuel consumption. For a longer tyre life, set the tyre pressure up to 0.3 bar above the recommended pressure. Check and set the correct pressure at least once a month.

4. Rotate your tyres every 5,000 – 8,000 miles.

Not all of the tyres on a car get the same amount of wear when driving down the road causing them to wear more quickly in some positions on the car than in others. Rotate your tyres every 5,000 to 8,000 miles moving them from front to back and left to right to take advantage of all available rubber on the tyre’s tread.

5. Store tyres properly. 

When storing tyres, make sure they are kept in storage at a stable temperature, away from direct heat exposure or a very cold environment.

A new car tyre has approximately 8-9mm of tread depth initially. Legally, you can drive on the road if the minimum tyre tread depth reaches 1.6 mm, across 75% of the tyre’s width and all around its circumference. As braking performance progressively declines with lower tread, it is prudent to check your tyres regularly, reduce your speed on wet and snowy roads and consider replacing your tyres in good time. 

Need Expert Assistance with Your Tyres?

tread grooves

Ensuring your tyres are safe is of paramount importance. If you’ve realised your tyres might be nearing their limit or if you just want to ensure they’re in optimal condition, don’t wait. Visit our tyre services page now to discover how we can help you maintain, check, or replace your tyres, ensuring your safety and compliance with UK standards. Remember, the safety of you and other road users is a priority. Let us assist you in making every journey a safe one.


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