AAA is encouraging drivers to replace their tires before the tread reaches 2/32-inch of depth, which is the industry standard.
According to the Connecticut Department of Motor Vehicles, a tire must have a minimum of 2/32-inch center tread in order to pass inspection.
A study released Thursday by AAA finds risks at twice that depth - 4/32-inch.
“AAA wanted to find out at what point does a tire become unsafe,” said AAA of Greater Hartford spokesperson Amy Parmenter.
AAA first tested a vehicle with new, all-season tires in wet road conditions. It then performed the same test with tires that were worn down to 4/32-inch of tread.
The test showed that the vehicle with worn tires took almost twice as long to come to a stop as the vehicle with new tires, and traveled an additional 87 feet.
AAA also said 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.
“This research is about raising awareness. We want drivers to understand that they shouldn't just go by the law and what the law says is safe," Parmenter said.
The grooves on a tire are designed to expel water from beneath the tire. When the tread is worn down, the tire can’t grip the road surface. That can lead to hydroplaning, which is when the vehicle skims on top of the water, causing the driver to lose control.
Will Rivera at Town Fair Tire in West Hartford said tires are one of the most important parts of a vehicle, along with the brakes and the motor.
“The industry standard is at 2/32-inch they have to come off. But when you get to 4/32-inch or even 3/32-inch, basically the tire’s just about on its way out,” Rivera said.
He said the average life of a tire is between 40,000 and 45,000 miles. However, the type of tire, type of vehicle and individual driving habits also factor in.
AAA said its research found that tire performance does vary by brand, but price is not necessarily an indicator of quality. Worn tire performance deteriorated significantly for all tires tested, including those at a higher price point, according to AAA.
To determine whether your vehicle needs new tires, AAA recommends using a quarter in place of the traditional penny test, which is based on the standard 2/32-inch of depth.
The process is the same. Put the coin into the groove, with the head pointing down.
“If any of his head is hidden, then your tires are good to go. But if you can see all of George Washington’s head, then you need to spend some George Washingtons and get yourself some new tires,” Parmenter said.
NBC Connecticut reached out to the U.S. Tire Manufacturers Association by email for a response to the AAA study.
A spokesperson said, “The U. S. Tire Manufacturers Association recommends that tires be replaced when worn to 2/32-inch tread depth remaining anywhere on the tread face. USTMA agrees that safety is important and encourages drivers to perform monthly checks on their tires.”