Cracked Tyres: Why They Crack And How To Prevent It
Cracked tyres can lead to expensive replacements, as well as safety hazards
on the road. Here are 5 reasons why tyres crack, and how
you can prevent this.
Tyres are highly engineered pieces of equipment, designed to perform well for thousands of miles and withstand hardships both on- and off-road. Wear and tear happens gradually through heavy use. Barring punctures or gashes (some of which can be repaired), tyres should last for years at a time.
That makes it alarming when your vehicle's tyres begin to crack. Unlike other types of damage, cracked tyres may occur even when the vehicle isn't used (sometimes because it's not used), and there's very little you can do to repair this damage.
That makes prevention key. Let's explore why tyres begin to crack, and how to stop this from happening:
What Causes Cracked Tyres?
Several components work in tandem to ensure tyres are strong enough to hold the weight of your car, keep their shape under pressure, and withstand the natural friction of asphalt and debris. These components include:
- Plies - The fibres inside the tyre that give it flexibility, while still maintaining its structure
- Beads - Steel that's coated in rubber to create a seal between the tyre and the wheel rim
The rubber on the outside of the tyre is made up of numerous polymers that are knitted together to form molecules. Cracked tyres often result from these bonds breaking down.
The bonds are often weakened by one of these five elements, or a combination of several of them:
UV Rays Or Extreme Weather
The polymers in the tyre can expand in the heat and contract in the cold. When this is mild and spread out over time, very little damage occurs, as the tyres are designed to withstand normal weather changes. However, in extreme heat or cold, or when the weather fluctuates substantially from one to the next, that results in constant movement. This can weaken the bonds over time, which is when cracks begin to appear.
Direct UV rays can have the same effect. In fact, UV rays are a leading cause of cracked tyres, because it's extremely difficult for most people to store their vehicles fully in a garage or to park in the shade at all times.
However, recent technological advancements have created UV-resistant paint (or sprays) that can be used on tyres. If your car spends a great deal of time in the sun, shops like Autofusion can use the paint to help safeguard your wheels.
Degradation
Tyres are made of rubber, which is an organic material that breaks down over time (albeit slowly). Certain chemicals and compounds are applied when your tyres are made to reinforce them and slow down degradation. However, these won't work forever.
This is especially true for lower-quality tyres that are manufactured to be a cheap option for drivers. The lack of quality rubber, the simpler design, and the fewer high tier chemical reinforcements added mean that low-cost tyres are more likely to crack than premium varieties.
Age
As your tyres get older, the polymers naturally weaken and start to break down. This causes your tyres to harden and become brittle - and this loss of elasticity can mean cracked tyres. Even if your car hasn't been driven for a few years and is stored in a garage, the tyres can still weaken and crack.
It's actually more beneficial to drive your car on regularly, instead of leaving it parked. Occasional use allows the tyres to flex and the rubber to loosen up, which prevents them from "drying out" and cracking. Therefore, if the car is parked for a long time, the tyres are at greater risk of cracking.
Water
Rubber is mostly waterproof, but water can still permeate the tyre after driving on wet roads for a prolonged amount of time. This water can then get inside of the tyre and slosh around – wearing it down from the inside – or freeze when the temperatures drop.
As the water expands and contracts in these conditions, it can result in partial cracks for your tyres. The wetter the tyre is, and the more adverse the weather is, the larger the cracks will become.
Tyre Pressure
If your tyres are inflated incorrectly, cracking may occur. With under-pressurised tyres, more heat is created when you're driving, because more surface area is in contact with the road. This creates extra friction. Likewise, the fibres are put under greater stress from both the weight of your car and the natural wear and tear of the road, since the tyre is unable to maintain its intended shape.
In contrast, over-pressurised tyres experience unnecessary stress at their sidewalls, and this can cause bulging. With too much force being exerted outwards, it can lead to cracks.
You can check whether your tyres are the right pressure using a pressure meter, or through Autofusion's tyre pressure checking tool. Simply input your car's registration number to receive your recommended tyre pressure.
Are Cracked Tyres Dangerous?
You should not drive with cracked tyres. Much like a punctured or flat tyre, doing so can lead to blowouts, damage to the wheel wells, and loss of control in your vehicle. The tyres' rigidity and strength have been compromised if they are cracked, and they will only become more damaged through use.
If you notice cracks around your tyres, you should take your car to a garage and have new ones fitted.
Are Cracked Tyres An MOT Failure?
An MOT test will involve all four tyres being checked for damage, as well as general wear and tear. To pass, your tyres should have a tread depth of at least 1.6mm (the legal minimum) and there shouldn't be any tears, bulges, or cracks around the tyre.
Your car may receive an MOT failure if it's determined that the tyres aren't safe to drive with. If your car does pass its MOT, your test-giver may still recommend a service check, as the tyres may be borderline on hazardous and need replacing soon.
To avoid a failed MOT test (and save the time and money that entails), you can check in with a shop like Autofusion in advance. A trained mechanic can assess your tyres, their tread, and any potential cracks. With their expert opinion, you can better understand if the tyres are in drivable condition or need urgent replacement. According to the depth of the cracks, the tyres may still be okay to drive, but an expert is needed to confirm this.
How To Fix Cracked Tyres
You should not try to fix cracked tyres, especially those which brandish cracks near or on the sidewalls. Their structure has been permanently weakened and no amount of chemicals or patches will return your tyre to its safe, stable condition.
How To Make Tyres Last Longer
With that said, there are preventative measures that you can implement while your tyres are in good condition to prevent them from cracking:
- Ensure that your tyres are inflated to the manufacturer's recommendations
- Drive your vehicle regularly
- Where possible, try to park in the shade or in a garage
- Apply a tyre protector regularly (some are made to protect the rubber from UV and environmental damage, as well as repel dust, dirt, and water)
- Only use water-based solutions to fortify your tyres, as harsh chemicals may speed up the cracking process
- Clean your tyres regularly to prevent fungus, mould, moss, or other rotting factors from damaging them
Having a qualified professional check your tyres will help them to last longer. Come down to your local Autofusion centre for a free tyre check and recommendations on preserving your tyres' lifespan.