Photo credit: Alex, Flickr.
To put it simply, bald tires are not safe. A car with bald tires may not break down after driving 200 miles on the highway, but bald tires can cause a lack of control, hydroplaning, blowouts and understeering. Bald tires in wet weather increase stopping distance.
First, let’s talk about what constitutes a “bald” tire. Tires that are below the legal limit of 2/32” tread depth. Tread is the amount of rubber on the outside of a tire, and it wears off over time. Much like the sole of your shoe can affect your safety when walking (ever try wearing smooth-soled boat shoes on ice?), tires make a big impact on how much traction your car has with the road. More traction equals more control.
“Driving on bald tires is not worth the risk,” said Sarah Robinson, Michelin tire safety expert and race car driver. “You lose significant grip, especially in wet weather which can cause hydroplaning.”
Hydroplaning is a fancy term for when a car skips across the surface of water on the road, rather than staying in contact with the road. It essentially means the driver has no control over where the car is headed, until the tires hit the road surface again.
Bald tires are very, very, very, prone to hydroplaning when in contact with water, said Joe Maher, product manager at Continental Tire.
But Maher said it’s hard to predict when a bald tire will go flat. But tires without enough rubber left on them have “significantly less traction on them” than tires with treads. “You may only need the extra traction once at 50 mph but that’s when it’s very important,” he said.
If you want to see if your tires are bald or not, Robinson suggests the “Penny Test.” Stick a penny upside down in the tread grooves. If you can see the top of Lincoln’s head, it’s time to buy new tires.
The tire wear indicator bar is visible on this really bald tire on the left.
Newer tires have a tire wear indicator bar, said Maher. These are barely visible when tires are new, but become apparent when the tread wears down. Also called wear bars, you’ll see a line across the groves indicating new tires are needed.
Another potential problem with worn tires is that they can run over something and get a puncture, which could cause a tire failure, said Woody Rogers, product information specialist at Tire Rack.
Rogers said it also gets harder to stop in the rain on bald tires. Tires worn down 75% go about 50 percent further before stopping than the same tire when new. Bald tires take almost twice as long to stop as the same tires when new.
Worn tires on the front cause understeering, which is another term for the car not going where the driver wants to go. It can be pronounced in situations like getting on or off the highway at a cloverleaf for example. With bald tires on the front, the driver could turn the steering wheel and the car won’t turn the expected amount. The situation is worse when bald tires are on the back, the car can spin out of control or oversteer. With oversteering, the rear tires slide and the car spins in circles, cautions Maher. For a good explainer of under- and over-steering, check out this Michelin video:
Here’s another ingredient in this recipe for disaster: Summertime heat. Rubber wears off more quickly when hot. When a tire is bald in the summer, it can make a perfect storm and create dangerous situations such as blowouts, said Robinson.
Tire problems cause 9 percent of all accidents, according to NHTSA’s Crash Causation Survey. Issues included tread separations, blowouts, bald tires, and underinflation.
Robinson suggests when there are bald tires on the front and there are good tires with tread on the back, the situation could have been prevented by proper tire rotation and checking air pressure. When tires are maintained, they wear evenly.
All the tire experts agree that when tires are bald, new tires are needed.
“Buy new tires now, you’ll be safer and so will the rest of us on the road with you,” said Rogers.
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Photo credit: The Tire Zoo.