Tire sidewall blowout may occur because of:

  • Under-inflation
  • Overload
  • Tire wear (especially uneven)
  • Damage
  • Age
  • Manufacturing defects.

According to the National Transportation Safety Board report, around 33,000 accidents happen annually because of tires. At least 2,000 of them are sidewall blowout-related, so it’s critical to know why the issue may occur.

Tire Sidewall Blowout Causes

Under-Inflation

Under-inflated, overly-inflated, proprly inflated tires
Image source: www.herbchambersmercedesbenz.com

Under-inflation may become an issue because of a driver’s negligence or damage. Any tire loses air over time – usually 1-2 psi per month. About 1 psi also goes away with every 10°F drop in temperature. If the tire has damage, air loss may be significantly larger, causing extreme lack of pressure sooner. Most tires have about 30-35 psi pressure standard, and if under-inflation reaches over 25%, a tire sidewall blowout may occur.

Under-inflated tires’ sidewalls flex more, as there isn’t enough pressure to hold the load of the vehicle, passengers, etc. This causes heat buildup, in addition to the existing high temperature that the tire usually can safely dissipate. This is especially dangerous at highway speeds and in warmer months. And if the temperature becomes too high for the tire to handle, it may fail any moment.

If you have experienced such an issue, the inner liner may help you identify the cause. If there are burnt rubber chunks missing from the liner, the tire sidewall blowout has most likely occurred due to under-inflation. In this case, tire manufacturers and insurance companies may refuse to repay the damage or replace the tire for free.

Tire Pressure Monitoring System (TPMS)

Tire Pressure Monitoring System tracks how much air there is in the tires and warns when it reaches a recommended limit. All vehicles manufactured after 2007 must have the TPMS built in. The goal of the system is to warn drivers about the issue and help avoid accidents due to tire failure.

Tire pressure monitoring system alarm
Image source: www.autoserviceprofessional.com

However, according to a survey, one in 10 car owners said they just ignored the warning light. Moreover, 42% of drivers can’t identify the problem at all or understand the signal.

Overload

When you drive an overloaded vehicle, the tires can overheat and explode. The vehicle also becomes less stable, so it may be more troublesome to drive out of a tire sidewall blowout. Driving at high speeds while overloaded only adds to the heat of the tire, so the accident may become inevitable. The problem is more common among SUVs and pickups, as they may carry heavy loads.

To learn more, look at your vehicle’s door for an information placard and search for the maximum load and inflation. The load mentioned can only be safe to transport if you inflate your tires, while cold, to the maximum. Your vehicles’ and tires’ maximum capacities must not be exceeded as the tires may not withstand the mass.

Info placard on a vehicle door
Image source: bridgestone.com.sg

Ideally, the tires have to be of the same load capacity as mentioned on the vehicle placard. The information on the tire’s load index is molded into its sidewall as a part of the tire code. Decipher the code using a table and note that the numbers show the capacity for one tire. So, to learn what mass your tires can transport, multiply the given number by 4.

Load index on a tire sidewall
Image source: www.discounttire.com

NOTE: Don’t think those numbers are a norm. That is the maximum limit of the tires, and every extra pound may become the cause for a tire sidewall blowout.

Tire Wear

Driving on bald tires make them heat up faster, and showing cords mean the tires can fall apart any minute. They are more vulnerable to damage, and any road curb can cause rapid air loss and result in a blowout.

The legal minimum tread depth in most states of the US is 2/32”, and a commentary suggests that’s already too shallow. After the depth reaches 4/32”, even a small pothole or a nail can cause a tire sidewall blowout.

Uneven Wear

While many drivers notice when their tread wears out completely, it may be more difficult to spot irregular wear. However, any wear pattern can cause cord exposure while the rest of the tread may still be in a good condition.

These are the main irregular treadwear patterns:

  • One-shoulder/edge.
    The tire wears more on one side, meaning there’s trouble with wheel alignment.
  • Two-shoulder.
    The tire wears more on both sides, meaning it’s under-inflated.
  • Center.
    The wear is more visible in the center, meaning the tire is over-inflated.
  • Cupping.
    The wear is in irregular spots across the tire, meaning it’s out of balance or there are problems with suspension.
  • Feathering.
    One side of the rib is sharper than the other, meaning there are issues with wheel alignment.

    Uneven tire wear patterns
    Image source: freeasestudyguides.com

If you notice any of these, replace the tires, as even when a specialist fixes the problem, the wear pattern may remain. Eventually, a hole may develop in the tire, through which it may lose air, which will cause a tire sidewall blowout.

Damage

Damage can develop due to road hazards or improper installation/maintenance. Usually when damaged, tires lose air more rapidly, resulting in blowouts, tread or belt separation, etc. Road hazards include potholes, debris, and curbs, which can leave a cut or a puncture in the tire. The damage may be immediate, making the tire go flat or explode, or it may be long-lasting. The latter will expand and eventually deflate the tire fully, causing a tire sidewall blowout.

What some of the damage can mean:

  • If you see a bulge on the tire’s sidewall, check the inner side. You may find a cut that releases air in between the plies, due to which the blister has occurred.
  • If you see a hole in the tread, this may be due to poor road (large holes) or debris (smaller ones). Both are quite dangerous as they may expose inner plies.
  • If you see a deep cut, the tire may have run on sharp debris. Such damage will provide permanent air loss and can cause an immediate tire sidewall blowout if it expands.

NOTE: Low-profile tires are especially vulnerable to road damage as their sidewalls are shorter and can’t absorb as much impact.

As for the damage due to improper installation or maintenance, these include uneven wear and bead chunking. The wear may become irregular due to tire misbalance or negligence of rotation. Bead damage is usually a sign of improper mounting – lack of lubricants when the tire is fitted on the rim.

Age

According to tire companies, a tire is safe for 6-10 years from the date of manufacture. Rubber starts to deteriorate from the moment it’s exposed to oxygen and heat. Due to degrading, rubber loses its flexibility and becomes more brittle. Its connection to the inner plies may weaken, and its vulnerability increases. It can’t withstand as much heat as it would usually, which increases the risk. So, even if the tire has plenty of tread left but is old, the risk of a tire sidewall blowout multiplies.

NOTE: Remember that the oxidation process applies for all tires, so they age even if not used.

Learning Tire Age

Date code on a tire
Date code on a tire sidewall.

You can find the date of the tire’s manufacture by looking at its DOT code. The last four digits represent the week and the year of manufacture. So, a tire with the date code 1612 was released during the 16th week of 2012. Since it’s already 5 years old, its owner should conduct a full inspection of its condition every year. You can learn more on tire date codes from this article.

Defects

The main defect that may cause a tire sidewall blowout is an inadequate speed rating. The lack of proper testing before the release may leave the tire with a lower speed rating. It can also act inadequate when loaded, resulting in overheating.

Furthermore, the following manufacturing defects can also contribute into a blowout:

  • Improper compound balance or impurities/moisture getting into the tire during manufacture. They may result in a radial tear of the tire going from the bead to the tread. The tear may appear as a tire sidewall blowout, causing an accident.
  • A broken connection between the belt ply and the tread. The main resulting damage is a bulge straight along the tread. It may eventually tear and cause a blowout.
  • Tire inadequately overheating and creating blisters between the tire plies. This may cause chunks of rubber to fall out of the tire’s tread. If you can see its cords in the hole that remains from the chunks, consider the tire dangerous.
  • Defects like the following can all cause tread separation and tire failure:
    • Moisture or foreign matter (dirt from the hands of a worker)
    • Out-dated skim stock (a layer between the plies)
    • Poor-quality solvents used to restore old skim stock
    • The lack of nylon overlays (an extra safety belt between the steel belts and the tread)
    • Inadequate final inspection of the tire.
  • Mistakes in design or compromising of the rubber compounds. These can result in the tire debeading off the rim and then full deflation.

If you are sure a tire sidewall blowout has occurred due to manufacturer’s negligence or a tire defect, you may contact a lawyer to get help in proving you received an inadequate tire.

What to Do If a Tire Sidewall Blowout Occurs

If a tire sidewall blowout occurs, follow these steps:

  1. Maintain speed to preserve vehicle momentum, by pressing the accelerator pedal or keeping the same pressure on it.
  2. Compensate for the instability brought by the blown tire. Counter steer the pulling to keep the vehicle in a straight lane.
  3. When you stabilize the vehicle, slow down and pull over to the side of the road.
  4. Turn the hazard lights on.

NOTE: Please, note that these actions are strongly recommended, and there were tests that have proven their efficiency. However, there’s no guarantee that this algorithm will definitely help you avoid an accident.

NOTE: The most important thing after a tire sidewall blowout is to not hit the brakes once you feel the explosion. This will destabilize the vehicle and can lead to serious consequences.

Also, prepare yourself for possible tire failures by:

  • Eliminating distractions when driving.
  • Not driving overloaded and at the top limit of speed, knowing you havetire damage.
  • Trying not to panic if you hear a strong sound and feel the vehicle starting to decelerate.

Things to Do to Avoid a Tire Sidewall Blowout

There are some things to include into your tire and vehicle maintenance routine:

  • Check tire pressure once a month.
    If you own a car with the TPMS, use it to help you maintain the recommended inflation. If not, check the pressure with a gauge every month and inflate the tire when it’s cold. The recommendations on the car door jamb are for cold tires, meaning they are in a stationary position and not heated. Also when checking, look for punctures that may cause air leak and cause a tire sidewall blowout faster. Soapy water can help you detect leaks as it will form bubbles where they are.
  • Match tire load and speed ratings to the vehicle recommendations.
    Check whether the codes on your tires match to those on the door jamb or other parts of the vehicle. Tires with higher load indexes and speed ratings are better reinforced and can withstand rougher conditions in terms of temperature.
  • Avoid heavy road hazards.
    Even reinforced tires may get damaged if you neglect to avoid a large pothole. If they aren’t visible on the outside of the tire, it doesn’t mean there are none. The inside damage may also become the cause of a tire sidewall blowout.
  • Have a technician inspect your tires.
    A professional may notice something you might have missed. A developing uneven wear or a small puncture may cause more serious issues. The tires may need rebalance, rotation, or repair, to prevent future issues.
  • Don’t use old and worn out tires.
    Tire-related accident risk increases as the tire ages and wears out. At full tread depth, the rate of tire-related crashes is 2.4%, compared to worn our tires with a crash-rate of 26%. Specialists recommend buying new tires when the old set reaches 4/32” tread depth, while the crash-rating is about 8%.

When Do Most Blowouts Occur?

A tire sidewall blowout is most likely to occur from mid-May to October. The temperature in most states is high during that time, and all minor issues of the tires become more dangerous. Slight under-inflation may build up more heat, along with excess load and highway speeds.

However, the issue may occur at any time and under any circumstances, especially in the warmer states. Although many modern tires can last for 60,000-80,000 miles, they will only do so if properly installed, used, and maintained.