Why do tyres crack between their treads?

Created by Jonathan Fry, Modified on Thu, 22 May at 1:24 PM by Jonathan Fry

Key Points

Tyres often crack between their treads due to aging, which reduces rubber flexibility.
Research suggests environmental factors like UV light and temperature changes accelerate this process.
It seems likely that improper tyre pressure and lack of use also contribute to cracking.

Why Tyres Crack Between Treads

Tyres crack between their treads mainly because the rubber ages over time, losing its flexibility and becoming prone to cracks. This natural wear is worsened by exposure to sunlight, ozone, and extreme temperatures, which break down the rubber. Additionally, mechanical stress from underinflated or overloaded yires can cause cracks, especially in the tread area, which flexes a lot during driving. Tyres that sit unused for long periods may also dry out and crack more quickly.

Importance of Maintenance

Keeping tyres properly inflated and driving regularly can help slow down cracking. If cracks appear, especially deep ones, it’s wise to have a professional check them, as significant tread cracking can be dangerous and may require replacement.

Survey Note: Detailed Analysis of Tyre Tread Cracking

Tyres cracking between their treads is a common issue that affects vehicle safety and performance, often signaling underlying problems with tyre health. This section provides a comprehensive exploration of the causes, contributing factors, and implications, drawing from various reliable sources to ensure a thorough understanding.

Understanding yire Structure and Cracking Locations

Tyres are composed of rubber compounds designed to withstand road conditions, with the tread being the part that contacts the road, featuring raised blocks separated by grooves. Cracking between the treads refers to fissures appearing in these grooves or on the tread surface, distinct from sidewall cracking, which is more common but less dangerous in some cases. The tread area is particularly vulnerable due to constant flexing and stress during driving, making it a critical area for inspection.

Primary Causes of Tyre Tread Cracking

Research consistently points to aging as a primary cause, with rubber compounds naturally degrading over time. This degradation reduces flexibility, leading to cracks. For instance, Tyre Outlet: Cracked Tyres - When They're Unsafe notes that cracks between treads are a sign of aging rubber, compromising structural integrity. The evidence leans toward environmental exposure as a significant accelerator, with UV light, ozone, and temperature fluctuations breaking down rubber polymers. Michelin: FAQs - Answers to Common Tyre and Assistance Questions highlights that prolonged exposure to sunlight and heat exhausts the tyre's oxidation agents, resulting in cracking.

A table summarizing key causes and their impacts is provided below:

Cause	Description	Impact on Tread Area
Aging	Natural degradation over time reduces rubber flexibility.	Leads to surface cracks, especially in grooves.
UV Light and Ozone Exposure	Breaks down rubber polymers, accelerating aging.	Increases crack formation due to environmental stress.
Temperature Fluctuations	Expansion and contraction weaken rubber bonds over time.	Enhances cracking, particularly in flexing areas like treads.
Chemical Exposure	Oils, chemicals, and road salts degrade rubber compounds.	Contributes to tread cracking, especially in wet conditions.
Improper Tyre Pressure	Underinflation or overinflation causes excessive flexing and stress.	Mechanical stress leads to tread cracks, as noted by SimpleTire: Cracked Tires: Causes, Prevention, and How to Handle It .
Lack of Use	Tyres sitting stationary dry out, accelerating cracking.	Particularly affects tread area, as seen in discussions on Reddit: Is it normal to see tires cracking? Michelin Pilot Sport A/S .

Environmental and Mechanical Contributions

Environmental factors play a significant role, with UV light and ozone being particularly damaging. Mr Tyre: Tyre Cracks - Causes & Fixes for Cracked Tyres explains that hot and cold conditions cause rubber to expand and contract, weakening its structure over time. Wet conditions, such as prolonged driving on rainy roads, can also degrade quality, as water may breach seals and misalign wheels, worsening wear. Chemical exposure, such as from road oils or cleaning agents, further breaks down rubber, as noted by SimpleTyre, emphasizing the need for regular cleanings to mitigate this.

Mechanical stress is another critical factor, especially for the tread area. Improper tyre pressure, whether underinflated or overinflated, can cause excessive flexing, leading to cracks. Overloading the vehicle or aggressive driving habits, such as hard braking or cornering, add stress to the tread, increasing the likelihood of cracking. This is particularly evident in the tread area, which undergoes constant deformation during use, as highlighted by SimpleTyre.

Impact of Lack of Use

Tyres that are not regularly used, such as those on vehicles parked for extended periods, are prone to drying out and cracking. This is often referred to as dry rot, where the rubber loses its elasticity due to lack of movement. Reddit: Is it normal to see tyres cracking? Michelin Pilot Sport A/S includes community insights from mechanics noting that low mileage and outdoor parking accelerate cracking, especially between treads, due to prolonged exposure without use.

Manufacturing and Material Considerations

While less common, manufacturing defects can lead to premature cracking. For example, Tyre Outlet mentions that cracks on relatively new tyres may indicate defects, requiring immediate replacement. Discussions on platforms like Quora and BobIsTheOilGuy forums suggest that some tyre brands, including Michelin, have faced issues with cracking, potentially due to material quality, though this is not universally reported and may vary by model and production batch.

Implications and Safety Concerns

Cracking between treads is particularly concerning because it can compromise the tyre's structural integrity, increasing the risk of blowouts. Tyre Outlet warns that even if tread depth is healthy, cracks indicate potential trouble, necessitating professional inspection and often replacement. Mr Tyre notes that cracked tyres could fail an MOT if the cracking is extensive, emphasizing the safety implications.

Preventive Measures and Best Practices

To mitigate cracking, regular maintenance is crucial. Checking tyre pressure monthly, as recommended by Mr Tyre, can help catch issues early. Storing tyres in a cool, shaded area away from direct sunlight, as advised by Michelin, reduces environmental damage. Driving regularly, even for short distances, prevents drying out, and using water-based, non-silicone tyre dressings can offer some protection without harming the rubber, according to community advice on Reddit.

Conclusion

In summary, tyres crack between their treads due to a combination of aging, environmental exposure, mechanical stress, and lack of use, with each factor contributing to the degradation of rubber compounds. While aging is inevitable, proper maintenance and storage can significantly delay cracking, ensuring safer and longer-lasting tyres. For any signs of cracking, especially deep or widespread, consulting a professional is essential to assess safety and determine if replacement is necessary.

Key Citations