AAA: worn tires on wet roadways put drivers at significant risk

Drivers should think twice before driving on worn tires in wet conditions.

New research from AAA reveals that driving on relatively worn tires at highway speeds in wet conditions can increase average stopping distances by 43 percent, or an additional 87 feet.

Research showed a significant increase in stopping distance between new tires and tires worn to 4/32 in wet weather, but almost all states including Ohio have laws or regulations allowing for tires to be worn to half that, or 2/32.

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While AAA's research found that tire performance does vary by brand, price is not always an indicator of quality. AAA found worn tire performance deteriorated significantly for all tires tested, including those at a higher price point.

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

Last year, Ohio reported 92 traffic deaths occurred during rainy weather conditions, nearly double the number of fatalities on snowy and icy roadways.

"Tires are critical to driver safety. When in good condition, properly maintained and of the correct type and size, they enable a vehicle to accelerate, steer and brake safely under a side variety of road and weather conditions," said AAA Tire & Auto Manager, Jason Brown. "Because they are responsible for much of the handling and stopping ability, tires play a critical role in the optimal performance of many of the vehicle safety systems. 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."

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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 compared to new tires, tires worn to a tread depth of 4/32 show:

  • An average increased stopping distance of 87 feet for a passenger car and 86 feet for a light truck
  • A 33 percent reduction on average in handling ability for a passenger car and 28 percent for a light truck

"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," said Megan McKernan, manager of the Automobile Club of Southern California's Automotive Research Center.

"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 Brown. "Slip an upside-down quarter between your tire grooves and look at Washington's head if you can see all of it, it's time to start shopping for new tires."

Current industry guidelines and state laws and regulations recommend that drivers wait until tread depth reaches 2/32" to replace tires. Not only does this recommendation jeopardize a driver's safety, it minimizes manufacturer warranty costs and is often paired with environmental concerns. 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. AAA's comprehensive evaluation of tire tread laws and regulations across U.S. states found state requirements range from inadequate to non-existent.

In Ohio, state law mandates that all tires must have a minimum of one-sixteenth of one-inch depth of tread on the road surface (OAC 4501:2-1-06).

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In wet conditions, tires can completely lose contact with the road and skid, also known as hydroplaning. The lower the tread depth, the more likely a car will hydroplane.

AAA recommends the following tips for drivers when considering purchasing new tires:

  • Begin shopping for new tires when the tread depth reaches 4/32"
  • Keep tires properly inflated, rotating them on a regular basis and inspecting them at least once a month
  • Test tread depth by placing a quarter upside down in the tread of a tire; if the top of Washington's head can be seen, the tires need to be replaced.
  • When shopping for new tires, price alone is not a good indicator of better performance
  • Research prospective tire models through consumer reviews and understand tire ratings

For the full report, fact sheet and other information regarding this study, please visit the AAA NewsRoom at

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