Tread Depth Safety
Tread depth refers to the amount of tread remaining on a tire. This is calculated by measuring the distance between the top of the tread block to the bottom of the tread void. This number is normally displayed in 32nds of an inch but can also be measured in millimeters. The amount of tread remaining on a tire impacts handling, traction, and stopping distance. As a tire wears and the tread depth is reduced, these characteristics begin to diminish. This effect is amplified when driving in adverse conditions such as wet or slick roads.
As you can see on the stopping distance chart, tread depth affects how well your vehicle can stop, especially on wet roads. It is very important to be aware of how much remaining tread is on all of your tires and how it impacts you.
Released in 2012, the National Highway Traffic Safety Administration's (NHTSA) study “Tire-Related Factors in the Pre-Crash Phase” shows the direct correlation of low tread depth and an increased likelihood of being involved in an accident. Discount Tire and industry standards recommend replacing tires worn to 4/32nds and below and will not service tires worn to 2/32nds and below.
*The Michelin Premier tire lines do not follow the stopping distance portion of the above image as they are designed with technology for like-new preformance to 2/32nds of an inch.
- Learn more about measuring tread depth.
Tire Aging Safety
When it comes to tire aging, it is very simple: the older the tires are, the higher the risk for failure. Tires are made of rubber, which begins to break down over time.
A publication released in 2008 from the Rubber Division of the American Chemical Society entitled “Rubber Oxidation and Tire Aging - A Review,” goes into detail of how an aged tire has reduced crack growth resistance, which can lead to an increased rate of tire failure. As a tire ages, oxygen penetrates the rubber causing the rubber to start breaking down on a molecular level. The rubber begins to become harder and more brittle, losing its elasticity and strength.
After a point, the tire’s ability to carry weight is reduced and it could potentially fail. Even if a tire has never been put into service or has very little use, it has still been exposed to time and elements causing its integrity to be compromised.
The age of a tire can be determined by the DOT number stamped on the sidewall of every tire produced for street use. NHTSA has also conducted studies on tire aging and released findings showing a link between tire aging and the increased chances of tire failure.
Most tire and automobile manufacturers recommend replacing your tires between 6 and 10 years. At Discount Tire, we recommend replacing any tire that is 6 years or more past the date of manufacture and will not service tires that are 10 years or more past the date of manufacture.
- Learn more about tire aging.
- Read a study conducted by the NHTSA on tire aging.
- Read the NHTSA’s Report to Congress on Tire Aging.
Tire Inflation Safety and Load Capacity
A properly inflated tire is also important when it comes to tire safety. As documented by the NHTSA, an under-inflated tire increases the chance of tire failure. A tire must be able to hold the weight of not only the vehicle, but also any additional load the vehicle might be carrying, such as fuel, passengers, and payload. A tire alone does not have the strength to support this. As air pressure builds inside the tire, the sidewalls gain strength and with the proper air pressure, it can now support the vehicle safely.
An under-inflated tire cannot support the vehicle and quickly becomes compromised. Driving on an under-inflated tire will begin to generate excess heat causing the rubber to break down. Eventually, the tire will no longer be able to withstand the excess load and fail.
You must check your air pressure often to prevent driving on under-inflated tires. Discount Tire recommends you refer to your owner’s manual or vehicle placard to find the correct tire inflation for your vehicle.
All vehicles from 2008 to current come equipped with a tire pressure monitor system (TPMS) to help monitor air pressure and alert the driver if the pressure falls 25% or more below the manufacturer's recommended inflation.
Routine Tire Maintenance
Proper and timely tire maintenance is crucial to safety. All of the tires on your vehicle should be inspected, inflated, and rotated on a routine basis.
Inspect your tires every month. Inspecting your tires will help identify any damage or conditions that might impede your safety. By evaluating the remaining tread, your tires’ age, and overall condition, you can eliminate preventable risks that could potentially lead to an accident.
Check your air pressure every month. Inflating your tires will ensure they have the proper air pressure to sustain the weight of your vehicle. As mentioned before, an under-inflated tire highly increases the chance of tire failure.
Rotate your tires every 6,000-8,000 miles. Rotating your tires helps prolong tread life, thus maximizing the handling, traction, and stopping capabilities of your tires. This also requires removing the tire from the vehicle which allows for a more thorough tire inspection.