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When Tire Tread Depth Matters Most All of the cars we test on MotorWeek come with something else that's new: tires! Now that's logical since new tires give the best performance and safety. But what happens to those parameters when the tires are no longer new? Our FYI reporter Yolanda Vazquez looked into the wearing of tires and discovered an issue that cannot be ignored. – John Davis YOLANDA VAZQUEZ: It's the only thing that keeps your car on the road, yet it's often one of the most neglected areas of vehicle maintenance. KEVIN ROHLWING, SENIOR VICE PRESIDENT OF TRAINING TIRE INDUSTRY ASSOCIATION: I honestly believe people ignore their tires. They don't rotate their tires, they don't check air pressure on a regular basis. They're just not paying any attention to their tires at all. VAZQUEZ: Industry experts like Kevin Rohlwing say that's particularly worrisome considering how many worn tires are on the roads these days. ROHLWING: The government estimates that there are over 30 million tires that are on the road right now that have less than 2/32 of an inch tread depth, so we've got a significant number of tires out there right now that are deadly.
GOSS: When wear bars are level with ribs, the tire is beyond use. VAZQUEZ: MotorWeek's Pat Goss says tires often lose their footing long before they get to that point. GOSS: Letting a tire tread get that thin allows for hydroplaning, loss of traction and so on. VAZQUEZ: The most accurate way to tell if your tires are roadworthy is to use a tread depth gauge. They're small enough to carry and relatively inexpensive. Goss demonstrates how they work.
VAZQUEZ: Another more common way to check your tread depth is with the time-honored penny test. Simply insert the coin into the tread grooves. If you can see the top of Lincoln's head, the tire needs to be replaced. Although 2/32 of an inch is the industry standard, a new movement is afoot to increase the tread-depth limit to 3/32 of an inch or even 4/32. This means the old penny test would become obsolete, replacing it with the quarter. The concept is pretty much the same except you use the top of Washington's head as your minimum tread depth limit. Tire Rack, America's largest independent tire tester and mail order tire dealer, prefers the quarter test over the penny, claiming it's outdated and compromises safety. JOHN RASTETTER, DIRECTOR OF TIRE INFORMATION SERVICES, THE TIRE RACK: Our tests show it can take twice as long to stop when you're down to the penny level and that's really a risk.
Rohlwing says Tire Rack's test illustrates the importance of maintaining a good tire tread depth. ROHLWING: The most important benefit motorists can get from proper tire maintenance is going to be safety. Tires are the only thing that are between the vehicle and the road.
GOSS: The safety of you, all of the people around you and everybody in your vehicle depends on having good tires on the car.
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VAZQUEZ: Tires are considered bald or "legally worn out" when one or more of their grooves reaches 2/32 of an inch deep.
GOSS: This little shoe portion fits against the rubber of the tire, and this portion here goes down inside one of the grooves.
VAZQUEZ: The company tested that theory at a track near Reno, Nevada. During the first run, the driver hits the brakes on wet pavement with tires that pass the quarter test (roughly 4/32 of an inch). The second run involves penny-tested tires at 2/32 of an inch. There was a difference in braking distance. The second set of tires go way beyond the original stopping point of the quarter test.
VAZQUEZ: The Rubber Manufacturers Association is handing out these pamphlets filled with tire safety tips as part of a nationwide public education campaign. The goal is to urge consumers to be more responsible on the roads. Experts agree motorists need to take a more proactive approach in protecting their tires. If they do, they'll reap many rewards for miles to come.