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Why Summer Puts Your Tyres Under Pressure

Most drivers think about tyres when the weather turns cold and frosty, but the warmer months bring their own set of challenges. As air temperatures climb, so does the temperature of the road surface, and on a bright July afternoon tarmac can easily reach 50°C or more. Your tyres are the only thing connecting you to that hot surface, and they are working harder than you might imagine.

Heat causes the air inside a tyre to expand. A tyre that was correctly inflated on a cool morning can be several pounds per square inch (psi) higher by mid-afternoon. Add a fully loaded car, a long motorway drive and a bit of spirited cornering, and the stress builds quickly. Combine that with rubber that has already spent a year or two in the sun and you have the recipe for uneven wear, poor grip and, in the worst cases, a blowout at speed.

The good news is that checking your tyres properly takes about ten minutes and can be done on your driveway. Here is what to look at and why it matters.

Check Tread Depth Before the Roads Get Hot

Tread is not just there for wet weather. It channels water away from the contact patch, but it also helps the rubber deform and grip the road as temperatures rise. The legal minimum in the UK is 1.6mm across the central three-quarters of the tyre, but that is a legal limit, not a safety target. Most tyre specialists recommend replacing tyres at around 3mm for summer driving, because wet braking distances increase sharply below that figure.

To check depth, use a proper tread depth gauge or the wear indicator bars moulded into the grooves. If the rubber is level with those bars, the tyre is at 1.6mm and needs replacing immediately. A quick roadside trick is to insert a 20p coin into the main grooves: if the outer rim of the coin is visible, you are close to the limit.

• Measure at three points across each tyre: inner, centre and outer edge.
• Check all four tyres plus the spare, if you carry one.
• Look for uneven wear, which often signals wheel alignment or suspension problems.
• Replace any tyre showing cords or bulges, regardless of tread depth.

Uneven wear is worth taking seriously. If the inner edge of a front tyre is bald while the outer edge looks fine, you may have incorrect camber or worn suspension components. A wheel alignment check at your local independent garage is inexpensive and will save you the cost of premature replacements.

Inspect Sidewalls for Cracks, Bulges and Embedded Objects

The sidewall takes a beating from kerbs, potholes and speed bumps, and summer sunshine accelerates the ageing process. Rubber contains oils that keep it flexible, and ultraviolet light gradually breaks those oils down. A tyre that looks fine at a glance may have fine surface cracking that worsens with heat.

Run your hand around the sidewall and look closely for:

• Cracking or crazing – small lines in the rubber that suggest the tyre is drying out.
• Bulges or blisters – a sign that internal cords have separated, which is dangerous and means the tyre must be replaced.
• Cuts or gouges – deep damage that could worsen at speed.
• Embedded screws, nails or stones – remove stones carefully; leave screws in place and get the tyre inspected.

Also check the date code stamped on the sidewall. It is a four-digit number, with the first two digits showing the week of manufacture and the last two the year. A tyre older than six years should be inspected professionally, even if the tread looks healthy, and anything over ten years should be replaced regardless.

Set Pressures Correctly for Hot Weather

Correct inflation is the single easiest way to improve grip, save fuel and reduce the risk of a blowout. Under-inflated tyres flex more, generating extra heat, which is exactly what you do not want on a hot road. Over-inflated tyres wear in the centre and give a harsher ride with less grip.

Check pressures when the tyres are cold, meaning before you have driven more than a mile or so. The figures for your car are usually printed on a sticker inside the driver's door pillar or inside the fuel filler flap, and they often differ for front and rear, and for light versus fully loaded conditions.

• Use an accurate gauge rather than a forecourt machine that has seen better days.
• Remember that pressures rise naturally as you drive, so never release air from a warm tyre.
• Recheck monthly, and before any long journey or towing trip.
• Do not forget the spare, which loses pressure just like the others.

If you are unsure what pressures suit your car and typical load, pop into an independent dealership or servicing centre. They will check and adjust them for you, usually while you wait, and can advise on the best settings for a summer holiday with a full boot.

Watch Out for Heat-Related Blowout Risks

Blowouts are rare but they do spike in hot weather, and they are almost always linked to one of three things: low pressure, damaged sidewalls or overloaded tyres. When a tyre runs under-inflated at motorway speed in high temperatures, the sidewall flexes far more than it was designed to. The rubber overheats, the internal structure weakens, and eventually it can fail without warning.

Reduce the risk by checking pressures before you set off on a long trip, taking a break every two hours so tyres can cool, and keeping within your car's load limits. If you feel a vibration, hear unusual road noise or notice the steering pulling, stop somewhere safe and inspect the tyres.

If you are heading off on holiday with a car full of luggage and passengers, it is worth having a professional look over the whole set. An independent used car dealership or automotive servicing centre will check tread, pressures, sidewalls and alignment in one visit, and will tell you honestly whether you need new rubber now or whether you can safely get another season out of what you have. It is a small investment that pays you back in fuel savings, confident handling and peace of mind when the temperature climbs.