Tire Sidewall Cracking: What Causes Dry Rot in Tires and How to Prevent It

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Have you ever touched an old rubber hose and felt it crumble in your hands? Or maybe noticed that the tire on your wheelbarrow is full of splits and cracks, no longer able to hold air? Over time, the compounds in rubber tend to break down and compromise its integrity.

The rubber in your tires is no different.

Most drivers understand that tires wear out and you’ll need to replace your tires. Miles and miles of friction from contact with the road causes your tire tread to wear down. In time, the tread depth becomes insufficient to channel water from underneath your tires. Without proper maintenance, including regular tire rotations (roughly with every  oil and filter change), your tires wear out faster. Same goes if your vehicle is in need of a  wheel alignment. While some tires last longer than others – and your driving habits certainly play a role – your tires will eventually wear down. That’s when they need to be replaced.

But treadwear is not the only reason that tires need replacement. If your tires are looking weathered or cracked – signs of dry rot – you need new tires.

What is tire dry rot?

Unlike dry rot in a wall or window sill, where a fungus causes deterioration in the wood, dry rot in tires happens naturally over time and with exposure to the elements. Although advances in modern rubber compounds have made for tires that are more resistant to dry rot than those of old, all tires are susceptible to the condition. And once it occurs, there is no turning back the clock.

Dry rot allows air to escape your tires, which makes it difficult to  maintain proper tire pressure. Tires that are underinflated will not only wear faster than normal (and unevenly at that) but they also make for poor vehicle handling – steering and braking. A tire that is dry-rotted can also break apart, causing a  tire blowout on the road. In extreme – and extremely dangerous – cases, the tread on a tire with dry rot can separate entirely while you are driving.

What does dry rot look like on tires?

One of the first and most obvious signs that a tire has dry rot is the presence of cracks or splits in the sidewall. Excessive heat, harsh chemicals, severe temperature swings, lack of use, and just plain old age all conspire to cause the rubber compounds in a tire to come apart. If the condition is advanced, you might also notice cracking in the tread pattern. A dry rotted tire might appear or feel harder, more brittle than normal and pieces could even break or flake off. And you might see that the color takes on a more faded or grey tone.

Dry rot is not uncommon with trailer tires, especially if a trailer sits unused and in the sun for long periods of time. Trailers often see less preventative maintenance than cars do. Still, dry rot is not uncommon in automobile tires. Regular inspections can reveal early signs of decay in the tires on your car, truck, or SUV. If you inspect them yourself, look for cracks, discoloration, bulges, wear, or any other unnatural blemishes.

What causes dry rot on tires and how do you prevent tire dry rot?

Dry rot may be a natural occurrence over time, but you can take steps to delay its onset. In fact, you only need to stave it off until it is time for a new set of tires once the tread wears out. The more you can avoid exposure to harsh conditions, the longer you can expect your tires to last – at least when it comes to dry rot.

Prevention comes largely from understanding the risk factors of dry rot. Consider these tips for preventing the condition:

• Maintain your tires. Tires that receive periodic maintenance (such as tire rotation and balancing) are less prone to becoming dry rotted.
• Avoid exposure. Ultraviolet (UV) rays from the sunlight cause your tires to break down. Try to keep exposure to a minimum, especially in hot, arid climates
• Forget the harsh chemicals. It is important to keep your tires clean. But strong, petroleum-based chemicals can remove important agents in the rubber that are designed to fight oxidation and weathering. Instead, use only non-petroleum products or soap and water
• Preserve proper inflation. Underinflated tires cause many troubles, one of which is excessive stress on the tread and sidewalls that leads to overheating. Excessive heat, in turn, leads to cracking and could cause tire separation
• Use them. Lack of use is a prime condition for dry rot. When you drive on your tires, you keep them supple. Sitting unused is not beneficial to your tires
• Do not overload them. Similar to underinflation, overloading places undue stress on your tires and will cause them to wear down prematurely. Make sure your tires are  properly rated. They should be the  right tires for your specific vehicle type and use
• Store them properly. Some people store extra tires (such as winter snow tires) when they are not in use. If this is the case, make sure to keep them out of direct sunlight, away from ozone-generating equipment (electric motors, generators, welding equipment, battery chargers), and not in extremely high temperatures.

What do you do if your tires are dry rotted?

Unfortunately, dry rot is not reversible. If you notice signs of dry rot – especially if it is advanced –

you need to  replace your tires. After all, they are the only thing between your three- or four-thousand pound metal machine and the road. Your tires are responsible for keeping traction with the ground in all sorts of conditions in order to get you going and, more importantly, to stop. The state of your tires is critical to vehicle safety! For you and for your passengers.

That is one reason that tire manufacturers recommend replacing your tires once they are ten years old, regardless of the condition of the tread. Just because you still have some tread life left in your tires does not mean they are safe. If they are beyond the ten year mark – or if they show signs of dry rot – avoid a catastrophic failure and schedule an appointment with your local and reputable auto mechanic to have your tires replaced as soon as possible.

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