How does warmer weather affect my tyres?

By Julia Freeman

There are many stereotypes out there that, frankly, aren’t true. The one about British weather being able to throw all four seasons at you in one day, however, is all too true. The weather system around this little island certainly likes to keep us on our toes, going from a chilly 4°C to a toasty 24°C almost overnight. But what affect does the warmer side of the British weather have on our car tyres?

warm weather driving

Temperatures across Great Britain may not reach the same levels as some other countries, and certainly no where near the temperatures seen in Death Valley, California, with a record high of 56.7°C in the summer of 1913, but summer temperatures in Britain can still sometimes be in excess of 30°C.
As drivers, we can often get a sense of security when driving in hot and sunny conditions – visibility is good, grip improves, and cornering speeds tend to rise. However, our safety relies heavily on the condition and ability of our tyres to perform when they’re needed to, so although many of us know to regularly check our tyres in the icy or wetter months, how many carry this over to the summer and consider hot weather tyre safety?

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Road temperature

When the weather is very hot, the dark asphalt on the road surface absorbs a lot of heat and reaches temperatures of 50°C. At these temperatures the road surface can actually begin to soften and even give the appearance of the road melting.
At the best of times, resistance and friction cause a build-up of heat inside tyres which makes the air within expand. With increased road surface temperatures the pressure will increase even further – causing the tyres to expand even further – and could lead to premature wear and possibly interfere with braking.

General tyre condition

Regularly checking the overall condition and health of your tyres during the warmer weather cannot be underestimated. The summer heat mixed with poor road conditions can make the rubber on your tyres softer than usual, resulting in the sidewalls being far more prone to damage or puncture.
It’s not just the sidewalls that the heat can impact as tyre tread can also be adversely affected by the warm weather. Although the UK’s minimum legal tread depth is 1.6mm, at Protyre we advise having a tread depth of 3mm or above to provide maximum summer safety for yourself, your passengers, and other road users.

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Tyre pressure in the heat

Think back to your science classes at school, and chemistry in particular. We were taught how things contract in the cold and expand in the heat, and car tyres are no exception to this. The general rule of thumb states that for every 10°C change in ambient temperature, tyre pressure increases by around 0.1 bar, even if the vehicle hasn’t been driven.
Although a fluctuation of 0.1 bar may not seem very much, the average car’s tyre pressure is usually kept at around 32 PSI which is approximately 2.2 bar – so even the smallest addition of air pressure can make a big difference to your tyres, particularly when you consider the combination of air temperature and road temperature. Heated air within a tyre can cause it to expand, eventually leading to a blowout and possible disastrous consequences.
The rubber on tyres is designed and engineered to have high resistance to low heat build-up, abrasion, and cracking but everything has its limits. Our tyre professionals recommend that you check your tyre pressure weekly during the warmer summer months, with daily checks during a heatwave.

What time of day should I check my tyre pressure?

Tyre pressures specified by the manufacturer are for cold tyres – meaning that the vehicle hasn’t been driven any further than around 3 miles in the last few hours. Therefore, we recommend you check your tyres either during the night or first thing in the morning before heading off on the school run or to work.
Once a tyre has been driven on for a few miles, it will have warmed up causing the tyre pressure to have increased slightly. At Protyre, years of experience has taught our tyre experts that you should avoid reducing the pressure of warm tyres too much, if at all, as once the tyre has cooled down it could cause the tyre to drop below the minimum tyre pressure.

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How do I find my tyre pressure?

Your first port of call to find the manufacturer’s recommended tyre pressure is in your vehicle’s handbook. Here you will usually be able to find guides for what tyre pressure to use with a normal load, as well as if you have an increased load, due to holiday luggage, towing, etc.
If you don’t have your handbook, often manufacturers will include a sticker or label somewhere on the vehicle with this information which can usually found on either the vehicle’s door edge, on the glove-box door, on the inside of the boot lid, or inside the fuel cap cover.

Talk to Protyre’s tyre professionals

If you have any questions about the condition of your tyres, our qualified and experienced tyre technicians will be happy to help. Either contact your local Protyre centre or book a free tyre check online today.
We stock a variety of tyres from a range of manufacturers to suit every budget – from the premium tyres of Pirelli and Goodyear to the more pocket friendly options from Falken and Sumitomo, we’re sure to have a tyre for you. With same day fitting available across much of our range, simply click the button below and type in your registration to find the best tyres for your vehicle.

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About the author

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By Julia Freeman
Julia is Head of Retail Marketing for Protyre and loves engaging with customers and the business as a whole to make sure Protyre is more than just a local garage.
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