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Christine Delise
Sr. Public Relations Specialist, MD
O: (410) 616-1900 (ext. 4361153)
C: (443) 244-7253

TOWSON, MD (June 8, 2018)Afternoon downpours or otherwise wet weather could spell disaster for drivers with worn tires – even though those tires may meet state regulations.

New research from AAA reveals that driving on relatively worn tires at highway speeds in wet conditions can increase average stopping distances by nearly 90 feet, or 43 percent more compared to new tires.


AAA’s testing of ‘worn’ tires involved a tread of four thirty-seconds of an inch (4/32”) in depth, but Maryland, and most state laws, allow for motorists to drive with tires that are even more worn at a tread depth of two thirty-seconds of an inch (2/32”), while Washington, D.C. and a few states have no minimum tread depth requirements at all.


“The tread depth of a tire literally determines how the ‘rubber meets the road’ and, therefore, how much control drivers will – or will not – have in wet weather,” says Chris Storms, AAA Car Care Center Regional Director. “The less tread, the less control. The less control, the greater the risk.”


It takes a vehicle with worn tires longer to stop.  AAA’s research showed that, if tested side-by-side at 60 mph on wet pavement, vehicles with worn tires would still be traveling at 40 mph when the vehicle with new tires had come to a complete stop.


With nearly 800,000 crashes occurring on wet roads each year, AAA urges drivers to check tread depth, replace tires proactively and increase following distances significantly during rainy conditions.


The AAA Research

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.

Laws and Regulations

AAA’s comprehensive evaluation of tire tread laws and regulations across the country found state requirements range from inadequate to non-existent.  Current industry guidelines and most state laws and regulations, including Maryland, state that drivers can wait until tread depth reaches 2/32” to replace tires, which AAA says is inadequate and can jeopardize a driver’s safety.  Maryland’s tire regulations (§ 22-405.5) can be found here on the Maryland General Assembly’s website:


By prioritizing safety, AAA maintains that tires should be replaced once the tread depth reaches 4/32”, when stopping distances have already begun to deteriorate significantly.


Comparing Tires by Price

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.


How to Test Your Tire Tread

Tire depth is measured in 32nds of an inch, with most new tires starting out at 10/32” or 11/32”.  “Measuring tread depth is one of the most important car inspections motorists can do and should be done monthly to uncover excessive or uneven wear before it becomes a safety hazard,” advised Storms.


AAA recommends a simple tire test to determine whether a vehicle needs new tires. Insert a quarter into the tread, leading with George Washington’s head. At least some of Washington’s head should be hidden in the tread or, AAA says, it is time for new tires. 


Motorists can always visit one of AAA Mid-Atlantic’s 11 Maryland Car Care Centers or a AAA Approved Auto Repair shop to have their tires inspected at no charge.


AAA Wet Weather Driving Tips

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 Mid-Atlantic 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.

The full report, fact sheet and other information regarding this study can be found on the AAA NewsRoom

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Mailing Address:
8600 LaSalle Road, Ste 639
Towson, MD 21286

AAA provides automotive, travel and insurance services to 58 million members nationwide and more than 937,000 members in Maryland.  AAA advocates for the safety and mobility of its members and has been committed to outstanding road service for more than 100 years.  The not-for-profit, fully tax-paying member organization works on behalf of motorists, who can now map a route, find local gas prices, discover discounts, book a hotel and track their roadside assistance service with the AAA Mobile app for iPhone, iPad and Android.  For more information, visit

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