A vehicle’s tires may be considered its most important safety feature. They serve as the contact point between the road and the vehicle, directly influencing the vehicle’s steering and handling, stability, traction, and braking systems. The effects of tire failure can be devastating. When a tire experiences abrupt failure, the driver may lose control of the vehicle while on the road. This is particularly dangerous when traveling at highway speed.
How Tires Are Made
As many as 200 different materials are used to create the average tire, including various types of rubber, special oils, silica, antioxidants, and more. These materials are combined in different amounts to fit the desired specifications for each type of tire. They are mixed thoroughly into a gum consistency by a computer-controlled machine.The next step is assembly. The inner liner is composed of dense halobutyl rubber that acts as the barrier between the pressurized air inside the tire and its internal components. Along a tire’s inner edges are the beads, which are made of steel and coated with rubber. Plies, or layers of strong composite fabric, make up the body of the tire. The plies are also coated with rubber to help retain air and bond with the other parts. Most tires in today’s market are steel-belted radial tires. To make these types of tires, two steel belts are wrapped around the body of the tire. The sidewalls of the tire help hold it together and allow a space for printing basic information. The tread is located on top of the steel belts and adjacent to the sidewalls. It is made of very tough rubber and is characterized by a blocked or lined pattern. The tread is the part of the tire that makes contact with the road while driving. Once the tire is assembled, it is cooked at 300 degrees Fahrenheit for roughly 15 minutes to cure the rubber and bond the different parts. Large tires may cook for up to a day. This process is also known as vulcanizing.
There are numerous types of tire defects ranging from inadequate tire design to poor manufacturing standards. Poor manufacturing standards may lead to insufficient tire bonding, which will ultimately cause tire failure. Poor manufacturing standards include:
- Use of old adhesives
- Improper cooking temperatures
- Contamination during production from moisture, sawdust, grease, or rust
Problems with the engineering and design of a tire can also result in tire failure. A common issue is the incorrect ratio or size of steel belts. Improper separation between tread and steel belts is another major design flaw. If a manufacturer defect results in injury to the driver, passengers, or other motorists, a recall should be issued immediately. The victims of an accident caused by a tire defect may also have a legal remedy against the manufacturer.
Tread separation occurs when a tire’s belts rip apart from each other. This causes the tread topartially or completely detach from the rest of the tire’s body while the vehicle is in motion. Tread separation typically occurs at high speeds, and it can lead to catastrophic accidents if a driver loses control of the vehicle. Insufficient tire bonding and other manufacturer defects frequently cause tread separation. In August 2000, Bridgestone and Firestone recalled roughly 14.4 million tires. This was the second-largest tire recall in United States history. The recalled tires posed major safety risks, and were cited as contributing causes to more than 100 deaths and 3,000 injuries resulting from tread separate accidents.
A blowout is typically caused by a puncture or cut in the sidewall of a tire. Blowouts may be the result of a defective rim that cuts into the sidewall or causes the bead to break. If the bead breaks, the tire slips off the rim. Punctures in the tire may also be caused by driving over a nail or other sharp object that embeds into the tire. Low air pressure is another cause of tire blowouts, which causes the tire to flex more than its design permits. The integrity of the belts is compromised as they begin to separate, and eventually the belts break out of place. Similarly, high air pressure willpush the limits of a tire’s design, and small disturbances like a speed bump can cause the tire to pop.
Other Types of Tire Failures
Sidewall Zipper Failure: This can happen during inflation of the tire and is characterized by the explosion of a tire’s sidewall. The failure derives its name from the zipper pattern that is typically seen after the damage has occurred.
Bead Fracture: One of the beads on a tire may get caught on the rim as the tire is mounted. The high stress this exerts on the bead can cause the bead to fracture. This results in a low-pressure explosion that frequently causes serious injuries including dismemberment, brain trauma, head injuries, and death.
Multi-Piece Wheel Explosions: While the majority of tires todayare made with single-piece wheels, multi-piece wheels are still manufactured and used. Multi-piece wheels have several metal components that rely on the tire’s air pressure to force them together. This translates to potential danger during mounting, repair, and vehicular motion.
Higher Risk of Tire Failure in Southern States
Research conducted on the geographic location of tire failure claims indicates that southern states witness a very high number of tread separations. The main reason for this disparity is that tires in southern states wear faster than tires in other areas due to the region’s high temperatures. Tires are mainly composed of rubber, which is made of long polymer molecule chains that give the rubber its elasticity. Over time, a tire can become brittle because oxygen molecules can break down these polymer chains. When the tire is exposed to excessive amounts of heat, such as a hot summer’s day, the molecule chains and material bonds within the tire will break down even faster. This accelerated degradation eventually causes cracks in the tire, particularly between the steel belts, leading to tread separation and blowouts.
Warning Signs of Tire Failure
It is possible to detect certain tire defects and potentially imminent failures due to these defects. If a vehicle owner experiences any of the following warning signs, he or she should take the vehicle to the nearest service center to have the tires examined by a qualified professional. Major indications of tire failure include:
- Unusual vehicle shaking while driving
- A thumping sound and/or vibration that appears to come from a tire
- The vehicle suddenly pulling to one side, often referred to as a “radial pull”
- Cuts or cracking in the sidewalls of a tire
- Uneven or excessive tread wear
- Blisters or bulges along a tire’s tread; early stages of tread separation can form a small bulge that continues to grow until tread separation occurs
- Tips for Owner Maintenance
While there are plenty of tire manufacturer defects that are out of a driver’s control, there are several precautions vehicle owners can take to maintain their tires. This will enhance the vehicle’s safety on the road. Maintenance guidelines include:
- Preventing under-inflation and over-inflation by regularly checking tire pressure
- Determining the age of your tire
- Ensuring that tires are regularly rotated, aligned, and balanced
- Having the tires regularly inspected for visible damage, including unusual cracks, bumps, and blisters
- Never driving on a flat tire for even a short distance; the tire’s integrity will be compromised
- Never repairing any sidewall puncturesor tread punctures larger than ¼ inch
- Checking tire tread by placing a penny between the tread grooves with Abraham Lincoln’s image facing forward and upside down. If Lincoln’s hair is not visible, the tires do not need to be replaced. If his hair is partially visible, it is almost time for replacement. If Lincoln’s entire head is visible, the tires should be replaced immediately.