New research from AAA reveals the dangers of driving on worn tires.
Driving on relatively worn tires at highway speeds in wet conditions can increase average stopping distances by a staggering 43 percent, or an additional 87 feet – that’s more than the length of a semi-trailer truck – when compared to new tires.
With nearly 800,000 crashes occurring on wet, snowy or icy roads each year, AAA urges drivers to check tread depth, replace tires proactively, and significantly increase your following distances during bad weather conditions.
“Tires are what keep a car connected to the road,” says John Nielsen, AAA’s managing director of Automotive Engineering and Repair.
“Even the most advanced safety systems rely on a tire’s basic ability to maintain traction, and AAA’s testing shows that wear has a significant impact on how quickly a vehicle can come to a stop in wet conditions to avoid a crash.”
In partnership with the Automobile Club of Southern California’s Automotive Research Center, AAA conducted testing to understand performance differences at highway speeds between new all-season tires and those worn to a tread depth of 4/32” on wet pavement. AAA research found that:
Compared to new tires, tires worn to a tread depth of just 4/32” exhibit:
- An average increased stopping distance of 87 feet for a passenger car and 86 feet for a light truck.
- A 33 percent reduction in handling ability, for a passenger car and 28 percent for the light truck on average.
How Tire Tread Impacts Driving Safety
“If tested side-by-side at 60 mph, vehicles with worn tires would still be traveling at an alarming 40 mph when reaching the same distance it takes for vehicles with new tires to make a complete stop,” according to Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center.
While AAA’s research found that tire performance does vary by brand, price is not necessarily an indicator of quality.
In fact, worn tire performance deteriorated significantly for all tires tested, including those at a higher price point. AAA advises shoppers to research options carefully before selecting a replacement tire for their vehicle, and never choose one based on price alone.
“With newer cars going longer intervals between routine maintenance at automotive service facilities, drivers may not become alerted to the fact their tires are too worn until it’s too late,” warned Nielsen.
Tire sizes can be confusing. Find everything you need to know about tire size measurement on the comprehensive ‘Tire Size Explained’ guide by TheVehicleLab, from tire specifications to wheel diameters and load index.
How to Measure Tire Tread for Driving Safety
Slip a penny or a quarter between your tire grooves and look at the head of Lincoln (penny) or Washington (quarter).
if you can see just the hair, your tires are okay. If you can see the full face, or most of the face, it’s time to start shopping for new tires.
Unfortunately, current industry guidelines and state laws and regulations frequently recommend that drivers wait until tread depth reaches 2/32” to replace tires.
According to the AAA, this recommendation jeopardizes a driver’s safety, while it also impacts the manufacturer warranty costs and is often paired with environmental concerns.
AAA maintains that tires should be replaced once the tread depth reaches 4/32”, when stopping distances have already begun to deteriorate significantly.
AAA’s comprehensive evaluation of tire tread laws and regulations across U.S. states found a state requirements range from inadequate to non-existent.
Dangers of Hydroplaning
In wet conditions, tires can completely lose contact with the road and skid, also known as hydroplaning. The depth of a tire’s tread plays a significant role: the lower the tread depth, the more likely a car will hydroplane.
AAA recommends the following precautions for drivers navigating rain soaked roads:
- Avoid the use of cruise control in order to respond quickly if the car loses traction with the road.
- Reduce speed and avoid hard braking and making sharp turns.
- Increase following distance to allow for ample space if a sudden stop occurs.
- If the vehicle begins to hydroplane, gently ease off the accelerator and steer in the direction the vehicle should go until traction is regained. Do not brake forcefully as this can cause the vehicle to skid.
When was the last time you checked your tire treads? Or rotated your tires?
Penny measurement photo courtesy Consumer Reports.