Tyres are your car’s only contact with the road surface. If these important components of a vehicle are overlooked for maintenance and safety checks, the results can be dangerous. 

Two possible outcomes in the long term are:

  • spending money on replacements earlier than normal or worse, 
  • a potentially hazardous accident caused by poor tyre conditions. 

It is the responsibility of every vehicle owner to make sure that they look after their tyres, not only for their own sake, but for the safety of passengers and pedestrians alike. There are two main tenets to keeping your tyres in top shape and safe. These are:

  • keeping the air pressure in the tyre at the correct level and 
  • tread inspection. 

That’s not to say there aren’t other checks you should be doing, but completing the above gives you the best chance of keeping safe.

tyre air pressure

Correct Air Pressure: When to Check 

In short, the air pressure of your tyres should be checked at least once a month and before you embark on any long journeys. 

To get the most accurate readings when checking your tyre pressure, it is recommended that you test them when they are cold – i.e. have not been driven on recently.

However, in our recent poll, we found that 15% of people did not know that they were to check their tyre pressure when they were cold (4).  

The reason behind this advice is that when tyres warm up – as they do due to friction with the road when driving – they expand, causing incorrect readings. 

Air Pressure Levels 

The recommended air pressure level for tyres varies – depending on the vehicle that it is mounted on. Of those we recently surveyed, 27% of people didn’t know where to find their vehicles recommended air pressure (3). 

To find out what the correct level is for your tyres, always check the handbook that came with your vehicle – if you can’t find the information, contact the tyre manufacturer directly and they should be able to help  you out. 

The correct pressure of air in your tyres relates to the size of the vehicle, the speed at which it travels and the handling requirements. Of those recently surveyed by Blackcircles.com, 11% of people never check their air pressures (6). 

Getting the pressure correct in your tyres is fundamental in maximising the safety features that it is designed to produce – i.e. responsive braking, strong grip and a long life. 

Incorrect Air Pressure 

If your tyres are over inflated this reduces the area of the tyre tread that encounters the road surface, which in turn speeds up wear and increases the chance of a tyre blowing out. 

Likewise, under inflated tyres also cause enhanced deterioration of the tread and shoulders. On top of this, the rolling resistance of the tyre increases, causing the vehicle to consume more fuel. 

A 7 psi (0.5 bar) difference from the vehicle recommendation given by manufacturers can reduce the lifespan of a tyre life around 8000km (8). 

Importance Of Tread Depth 

The tread on tyres is designed in such a way to offer good grip whilst driving. Some are produced with wet conditions in mind, others for use primarily on dry surfaces. 

Generally, the amount of grip that a tyre can offer a vehicle decreases as either:

a) they grow older, and the tread depth wears down or 

b) the level of water on a road surface is of a high volume. 

In the UK the legal minimum tread depth for tyres is 1.6mm across 75% of the width of the tread and around the whole edge of the tyre. Our recent survey found that 29% of people didn’t know the legal tread depth (1). 

To check that your tyres are legal you can either use a tread depth guide or, if you do not have one of these, use a 20p piece. If the tread depth is over the border of the coin, then the tyres are of a legal depth. The same survey found that this handy little tread depth test is known by 61% of people (2). 

Stopping distance

The stopping distance of your car significantly increases when your tyre tread is below the legal limit of 1.6mm. It also increases your chance of losing control on the road. Drivers should always bear this in mind when driving in adverse weather conditions. 

Tyre Maintenance 

A worrying statistic to come from one of our recent social polls was that 41% of people don’t check their tyres regularly for punctures and cuts (5).  

If the sidewalls of your tyres are affected by bulges or cracks, this is a clear indication that your tyres are colliding with potholes, curbs or possibly road debris. 

Cracks are a sign of external damage and bulges in the tyre are indicators that an impact has damaged the inner workings. If you spot these then have your tyres changed as soon as possible. The tyre is now weak and may fail. 

If you fail to regularly check your tyres – including air pressure, tread depth and condition – you run the risk of driving on tyres which are no longer road worthy.  Driving on illegal tyres can lead to a fine of up to £2,500 and the chance of three penalty points(9) on your driving license per tyre – a max penalty which only 32% of people knew when asked (7).  

If you are ever unsure about your tyres – many garages or tyre fitting centres will provide motorists with a tyre safety check. Allowing you to speak with an expert and have your tyres checked over. We also have lots of useful resources on tyre safety

Data and citations 

  1. 29% of 3,168 respondents gave the incorrect answer to the question ‘what is the legal minimum tread depth for tyres in the UK?’. Source: Blackcircles.com tyre safety quiz 
  2. 61% of 2,919 respondents answered 20p to the question ‘What coin can be used to test tyre depth?’ Source: Blackcircles.com tyre safety quiz 
  3. 27% of 3,507 respondents gave an incorrect answer to the question ‘where can you find the manufacturer recommended air pressure?’ Source: Blackcircles.com tyre safety quiz 
  4. 15% of 2,913 respondents gave an incorrect answer to the question ‘when should you check the air pressure of your tyres?’ Source: Blackcircles.com tyre safety quiz 
  5. 41% of 189 respondents answered ‘Nope’ to the question ‘Do you check your tyres for punctures etc regularly?’ Source: social media polls, split over twitter & Instagram. 
  6. 11% of 186 respondents answered ‘Never’ to the question ‘How often do you check the air pressure of your tyre?’ Source: social media polls, split over twitter & Instagram. 
  7. 32% of 2,973 respondents gave an incorrect answer to the question ‘What is the maximum penalty for illegal tyres?’ Source: Blackcircles.com tyre safety quiz 
  8. Source: https://www.michelin.co.uk/auto/tips-and-advice/advice-auto/the-importance-of-the-correct-tyre-pressure 
  9. Source: https://www.gov.uk/check-vehicle-safe
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