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What are Cracked Tires? Causes, Fixes, Prevention

Small tears or cracks to the sidewall of a tire are a common sign of weathering or ozone cracking and it's recommended to get the tire changed.

Driving on a cracked tire is dangerous as the strength and rigidity of the tire is compromised and could result in a blowout as you drive. If you have ever experienced a blowout, you know that it's dangerous and can cause a loss of control of the vehicle.

Tires are integral to your vehicle, after all, without them, you can't move. They have to be strong and robust enough to bear the weight of the car without losing their shape or flexibility.

Cracked tires occur when the polymers used to fabricate the tire weaken due to environmental, driving, or age-related issues.

How Tires are Made

Understanding the materials used to make a tire and how they work can provide greater insight into what makes them weaken.

  • Plies – Plies make up the tire's basic skeletal structure. They are composed of polyester on fiber cords that have been wound together and sandwiched in rubber. They provide flexibility.
  • Steel belts – The steel belts begin their lives as thin steel wires that get woven together to form thicker cords. These, in turn, are woven to form strong belts. Once sandwiched between rubber, 2 – 3 of them run longitudinally around each tire.
  • Beads – Rubber-coated steel that creates a seal between the tire and the wheel rim.
  • Chaffer – The rigid rubber plug that encases the beads that protect the plies from unnecessary abrasion.
  • Sidewall – Made from extra-thick rubber as it has all of the tires identifying information embossed on it.
  • Tread area – Thick rubber made from polymers that knit together closely to form molecules, laid over a cushioning gum layer for a softer ride. These are the bonds that break down over time resulting in crack tires.

Learn More: Tire Sizing

Hard tread has a long life expectancy but a reduced grip. Soft tread grips exceptionally well but tends to wear faster.

What Causes Cracked Tires?

cracked tires

Multiple factors combine and result in damaged, cracked tires:

UV Rays

UV rays found in sunlight are the biggest enemy of tires. Extreme heat weakens the bonds in the polymers by making them expand and contract. It is impossible to protect your vehicle all the time, although garaging it or parking in the shade whenever possible will extend the tire's life.

Age

Over time polymers will naturally weaken causing the tires to harden and lose flexibility. Once the elasticity decreases the tire becomes brittle and is prone to cracking.

You might think that the tires of an unused vehicle that's parked in a garage for long periods would be safe from harm, that isn't so.

The tires need some heat and natural lubrication to keep them supple. It's advisable to take the car out for an occasional drive.

Water

This is a strange one, as you would expect thick rubber to be waterproof. For the most part, it is. However, prolonged driving in wet conditions can allow the water to permeate the rubber, again, weakening the structure.

Tire Pressure

checking tire pressure

Under-inflated tires have a larger surface area in contact with the road. This increases the heat and therefore the friction.

Over-inflated tires add unnecessary stress to the sidewalls of the tire, resulting in bulging and cracking.

Manufacturing Defect

Although rare, this occasionally happens in younger cars. If your vehicle is relatively new, you should return to the dealership and ask for a professional inspection.

Degradation

Rubber is organic, its made from trees. As such, it will biodegrade over time, it is an irreversible process. Although protective chemicals and compounds are added during fabrication, over time they will wear away.

Can Cracked Tires Be Repaired?

There are varying levels of tire cracking, but the untrained eye may not be able to recognize the difference.

Fine cracks between the tread are often superficial and whilst they're not overly worrying, they can lead to worse issues, including loss of traction.

Although it is possible to repair cracked tires, we strongly recommend that you seek the opinion of a professional mechanic before you set about any work. They will be able to advise the extent of the damage.

How to Repair a Cracked Tire

Unlike a puncture, a crack isn't an isolated incident, it is usually a forewarning that the integrity of the rubber is comprised.

Small, discreet cracks that are mostly superficial are fixable; larger cracks mean that the tire is dangerous, and needs to be changed.

  1. Clean the area thoroughly, dirt removing sprays or carburetor cleaner are best for the job.
  2. Scratch around the area to create a rough surface that the adhesive will have no problem bonding with.
  3. When it is clean and dry, squeeze enough elastic cement from the tube to fill the crevice. Ensure you are using the type approved for tires.
  4. Use a plastic scraper to work the cement deep into the crack, and then scrape the excess away to leave a smooth surface.
  5. Leave to set/cure for the recommended time.
  6. Spray with two coats of black tire paint to seal and to add a layer of protection from the sun, dirt, and moisture.
  7. Make regular checks to ensure the crack has remained sealed and stood strong against heat, rain, and poor road surfaces.

How to Prevent Cracked Tires

While it is virtuously impossible to prevent minor tire cracking, many steps can be undertaken to prevent major damage.

Be sure to wash the tires in a mild soap and water solution or a dedicated tire cleaning product. Alcohol and petroleum-based cleaners can remove the protective layer that manufacturers apply, leaving the tire exposed to the elements. For the same reason, you should try to store the vehicle on a cement or similar base that is free from alcohol.

Carry out regular tire pressure checks. Keep the tires inflated to the recommended level. Both under or over-inflated tires can be prone to premature wear and tear.

Avoid parking in extreme weather conditions for long periods. Both freezing temperatures and excessive heat are enemies of tires. If the vehicle is going to be stored, try and keep it indoors and place some kind of matting between the tires and the ground.

If the car is in storage, drive it every couple of months. This is a requirement of most of the engine's components but it also helps to keep the tires healthy. The heat created by the rotation of the tires encourages the protective layer to do its job.

Unload any excess weight. Towing puts added pressure on the tires, but so does a fully-loaded trunk. Lighten the load to extend the service life of your tires.

Change your driving habits. High-speed braking, skidding, and speeding can increase the temperature of the tires which can aggravate existing cracks and encourage new ones to form.

How Long Do Tires Last?

This is a tough question to answer as there are many variables including mileage, driving styles, and environment.

However, it is widely believed that 10-years is the cut-off point, even if there's no evidence of cracking or dry rot. It is likely that the thread compounds have expired and will no longer be effective.

Is it Dangerous to Drive on Cracked Tires?

Minor cracks might look harmless but are often the pre-cursor to something more sinister. Any cracks should be checked out by a mechanic and the tire should be changed if they recommend it.

Cracks on the treads are not as dangerous as those on the sidewalls; these can lead to catastrophic failure of the tire (the same reason tire stretching is dangerous). The tread may separate as you drive or you could suffer a total blow-out and lose control of the vehicle.

Deep cracks can cause the tire to naturally deflate; under-inflated tires can quickly deteriorate.

Final Thoughts

UV exposure and oxygen are major contributing factors to tire degradation, along with vehicle storage and driving conditions.

Knowing what cracked tires are can help you to maintain tire health. The safety of the driver and the car occupants is paramount. This is easily achieved by recognizing when a tire is beyond salvage and should be changed.

Richard Reed
I've been a General Manager of a moving company and I've also been a Professional Mover for over 30 years. I've driven flat beds, reefers, dropdecks, moving vans, heavy machinery, etc. In my time as a Mover I've driven over 1,000,000 safe miles. My days of moving and driving truck are past me but The Vehicle Lab allows me to share the knowledge I've gained over the past 40 years.
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