Are you looking into buying used tires online? You might be looking at the images and thinking that you got yourself a deal – a cheap set of tires with a meaty tread. Unfortunately, the tread depth is only part of the story – tires also age over time, i.e., they dry rot.
You might have heard of the issue before, but it’s a real problem that plagues many tires that are still rolling on public roads today. And although it might not look dangerous on the outside, dry rot can significantly reduce the tire’s ability to grip the road, and it is a real safety issue.
But what is dry rot, and why does it occur in the first place? And can you do something about it? Well, there is a lot to discuss here! In this article, I’ll cover the dry rot basics but also go into more detail and tell you about the science of dry rot tires. So, buckle up because it will be a hell of a ride!
- Your Tires Silent Enemy: Dry Rot
- How Dry Rot Affects Road Safety
- The Effect on Your Vehicle’s Performance
- The Science Behind Dry Rot
- Preventing Dry Rot: Essential Care for Your Tires
- Myths and Misconceptions
Your Tires Silent Enemy: Dry Rot
The tires are perhaps the most integral part of your vehicle, as they are the thing that comes in contact with the road. As such, they undergo constant stress from various forces, like the vehicle’s weight, acceleration, cornering, and braking.
Moreover, tires are exposed to various environmental elements. And while they might look tough, tires are not immune to degradation. One silent and often overlooked enemy that poses a significant threat to tires is dry rot.
Dry rot is a form of rubber degradation that occurs slowly over a longer period of time. However, certain factors can accelerate dry rot, like a combination of natural aging, exposure to harsh conditions, and insufficient maintenance.
Regardless, dry rot can significantly affect the structural integrity of your tire but also the rubber’s properties. For instance, dry rot usually makes the rubber brittle, prone to cracking, and less sticky, which significantly affects traction.
1. How Dry Rot Starts
Essentially, dry rot begins with the breakdown of the rubber compounds that make up your car’s tires. The rubber in every tire has a different chemical composition, but regardless, each one will age, i.e., dry rot over time. The main cause of dry rot is the sun’s UV radiation, which can break down molecules and change the structure of the rubber. However, other factors also affect tires, like extreme temperatures and ozone.
However, you can also accelerate dry aging by not inflating your tires regularly. When tires are underinflated, they flex more than they should, which generates excessive heat. This can significantly reduce your tire’s lifespan by accelerating tread wear and causing dry rot. Conversely, overinflation can also contribute to dry rot by making the tires more susceptible to damage from impact, punctures, and wear.
2. What are the Indicators of Tire Dry Rot?
Recognizing dry rot in the early stages requires close inspection, and let’s face it, most of us drivers don’t do that. The majority of drivers that I know just look at the tread depth, not for any other issue. Still, close inspection is crucial, as it can reveal various issues with your tires, including dry rot.
The best early indicator for dry rot is small cracks appearing inside the tread grooves or the sidewall. These will be very hard to notice from a few feet away – you will need to look at the tire from a few inches away. Also, look for other indicators, like the rubber material fading, losing shine, or looking very dry.
Meanwhile, if the tire dry rot is at an advanced stage, you might see large cracks appearing everywhere on the tire. Moreover, the rubber will be very brittle and may start to crumble when you rub it off with your fingers. In some situations, the tread might start disintegrating while you are driving, leading to big chunks of rubber missing from the tire, revealing the inner layers. You can even notice air pressure loss, where the small cracks on the tire allow air to escape.
In case it is not obvious, you should absolutely stop driving if you notice those things and replace the tires immediately.
How Dry Rot Affects Road Safety
The real issue with tire dry rot is that it is a stealthy threat that only a few people will notice. Yet, it is a big safety issue, leading to many accidents, some even fatal, every year. Some experts even argue that Paul Walker’s fatal accident with the Porsche Carrera GT was because of the tires, which were nine years old, more than enough to cause dry rot.
So, here is how dry rot impacts your car’s performance and, with that, safety.
1. Decreased Traction
Dry rot impacts the flexibility of the tire, which can significantly impair longitudinal traction and lateral grip. Or, if you want it in layman’s terms, the tire won’t conform to the road’s surface or under load (braking, acceleration, cornering), resulting in reduced traction. This reduced traction can be particularly dangerous in wet or icy conditions, where maintaining control of the vehicle is crucial.
2. Impaired Handling and Braking
By making the tires less adaptive to the contours of the road, dry rot can also destabilize your vehicle while cornering. Usually, older tires snap more easily when they lose traction, leaving you no time for a reaction. This results in your car spinning out of control, which can be dangerous if it happens at higher speeds. Moreover, dry rot will make the tires less responsive and communicative and generally harder to drive.
3. Increased Risk of Blowouts
Dry-rotted tires are at a significantly higher risk for blowouts. As the rubber weakens, the internal structure of the tire is exposed to external pressures, like the vehicle’s weight, acceleration, braking, cornering, and the road’s imperfect surface.
All of this makes the tire prone to sudden failures, which usually happen at higher speeds or under heavy loads (towing and hauling). The fact that a blowout might happen when you drive on the highway or tow makes it even more dangerous.
4. Flat Tires
Tires with dry rot lose air more quickly than healthy ones. The small cracks that form allow air to escape, leading to underinflation or even a flat tire. This can leave you stranded if you only have a tire repair kit, as it won’t be able to seal the cracks. Even worse, it could lead to an accident if the tire loses pressure while driving.
5. Uneven Wear
Tires with dry rot will wear unevenly due to the compromised structure. Uneven wear can only add to the threat of driving on dry rotted tires, resulting in an even more rapid tire failure.
The Effect on Your Vehicle’s Performance
Dry rot doesn’t only affect the safety of your vehicle – it can also impact how it performs, the way it drives, and how much it costs to run.
1. Worse Fuel Economy
The stiff and brittle nature of dry-rotted tires can increase the rolling resistance by not letting the tire be in constant contact with the road. A higher rolling resistance means that your engine will need to work harder to keep a desired speed, resulting in higher fuel consumption and higher emissions.
In addition, tire dry rot can even affect your vehicle’s straight-line performance. Due to the less traction on offer, the tires will slip under hard acceleration.
2. Harsh Ride
Dry rotted tires are hard and brittle, which directly affects how they ride over bumps. This is because the tire’s ability to absorb shocks from the road has been impaired, which results in a very harsh and uncomfortable ride.
3. Vehicle Pulling to One Side
If tires on one side of your tires aged more quickly, maybe because they were exposed to the sun more, they could affect the balance of your vehicle and cause it to pull on one side.
The Science Behind Dry Rot
I talked a lot about why dry rot is a dangerous issue that needs immediate attention, but I haven’t told you what exactly causes it. Well, here are some nerdy details!
First of all, tire dry rot is a change in the rubber’s molecular structure due to oxygen atoms reacting with the rubber. Basically, it happens when the molecules inside the tire break down, thus changing the chemical composition.
Since dry rot mostly happens from excessive heat, UV rays, oxygen, and ozone, the scientific term is thermo-oxidative degradation. Here are all the steps that lead to it:
- Oxidation: oxygen (O2) is one of the most reactive elements in the universe. As such, it’s very important for life because it allows it to break down glucose and produce energy. However, this means that it also “breaks” about everything else, including the bonds in the rubber’s polymer chains.
- Ozonolysis: ozone (O3) is a form of oxygen with three atoms in its molecule, which is even more reactive. It does the same damage as regular oxygen, but only way faster.
- Evaporation of essential oils: modern tires have essential oils built into the rubber material to keep it flexible and protect it from external factors. However, with time, these essential oils evaporate, leaving the rubber molecules prone to damage.
- Cross-linking: all that breaking down of molecules that I mentioned before will make new bonds inside the tire. In other words, different molecules will start “cross-linking,” which completely changes the structure of the rubber and makes it harder. At that point, it’s basically a different material with different properties.
Preventing Dry Rot: Essential Care for Your Tires
Fortunately, you can prevent dry rot from happening, or at least mitigate it and prolong the lifespan of your tires. Some of the tips you read here are straightforward, but some will surprise you. Let’s have a look.
1. Mitigate Sun Exposure
Since the number one enemy of your tires is the sun’s UV rays, keeping them in the shade can greatly decrease the chances of dry rot happening. If possible, park your vehicle in a garage or shaded area. However, if outdoor parking is your only option, consider using tire covers to shield them from harmful UV rays.
2. Avoid Excessive Heat
Excessive heat can also accelerate dry rot, particularly in combination with the sun’s UV rays. Therefore, I recommend parking your car in a cool and dry place without a heat source nearby.
3. Protect Your Tires from Ozone
UV lamps, ionizers, or devices that create corona discharge produce ozone, which can significantly accelerate dry rot. Therefore, you should try to minimize exposing your tires to these devices or anywhere near their vicinity.
4. Use Your Tires!
Although it seems counterintuitive, using your tires will greatly mitigate dry rot issues. The flexing action that arises from all forces while driving distributes the protective oils in the rubber and ensures the tire remains flexible and pliable.
Meanwhile, keeping your car stationary will put more stress on certain parts of the tire, where dry rot could be accelerated. Thus, if you don’t plan on using your vehicle for a longer period (for example, if you have a classic car), remove the tires and store them in a cool and dry place.
5. Proper Maintenance
There are three things that fall under regular tire maintenance: regular inflation, rotation, and balancing. By doing all of these things, you will ensure your tires receive an even load across their surface, which reduces the chances of dry rot, but also ensures long treadlife and even wear.
I recommend checking the tire pressure at least once every month or more often if there is a big temperature change in your area. Tire rotation is recommended at each oil change or at 5,000-8,000 miles, while balancing is recommended whenever you replace your tires (like winter with summer tires) or once a year.
6. Professional Inspection
Whenever you bring your tires for a rotation or balancing, ask the tire technician to check them for cracks, bulges, tread separation, and other issues. Professional tire technicians can spot early signs of dry rot and recommend if your tires need to be replaced.
Myths and Misconceptions
Since the internet is flooded with opinions from just about every human on the planet, most of them will inevitably be wrong. So, let’s play some “Mythbusters” here and see what’s true and what’s false.
1. You Can Repair Dry Rot
I see many tire sprays claiming to rejuvenate tires and eliminate dry rot. However, these products only address surface cracking and can’t penetrate the rubber to completely eliminate dry rot. So, whenever you see significant cracking on your tires, I highly recommend replacing them. You could use those sprays as a preventative measure, though.
2. Old Tires with Enough Tread Depth as Good as New
I think you already know the answer here, but this is completely false. Tires age over time and should be replaced after 6-8 years, depending on the model. Look at the manufacturer’s recommendations to see what is the true lifespan of your tires.
3. Driving Frequently Will Accelerate Dry Rot
Again, this is false. Not just that, but the opposite is actually true – you should use your tires more to mitigate dry rot. Driving regularly will keep your tires flexible and more durable.
4. Only Cheaper Tires Suffer from Dry Rot
It is true that cheap tires suffer from dry rot more quickly than expensive premium tires. However, this doesn’t mean that the 10-year-old Bridgestone or Michelin tires you found online for the cheap are a good buy. Every tire suffers from dry rot eventually, particularly if exposed to the sun.
Dry rot is an unavoidable thing with tires. Just like we age, tires will also age over time, and external factors can accelerate that, i.e., the UV rays can also cause bond breakage on our skin and lead to various diseases, like cancer.
So, think of your tires as a living tissue that gets older over time and will eventually stop being usable. This might help you treat them better, like keeping them away from sun exposure, ozone, and high temperatures. By doing that, you will ensure they last longer and potentially save some cash!
But if your tires have already developed dry rot, it would be best to replace them. Not doing that is only looking for more problems – dry rotting will significantly reduce traction, which might result in a costly accident. In the end, you will be paying much more and still be left with an old set of tires!
I’m Ivo Gievski, the content writer for Tireer. We built our website with over 15 years of experience and extensive research in the automotive and technology sectors. My dedication to delivering high-quality content is unwavering, and I strive to continuously hone my skills to stay ahead of industry trends and provide readers with informative, engaging, and valuable insights.