Tire Tread Debate: Penny or Quarter?
Tens of millions of American motorists know the routine: to check if your tires are worn out, insert a penny in between two treads. If you can't see the top of Honest Abe's pate, it's time for new shoes. The Tire Rack says it's time to upgrade the coinage involved from a penny to a quarter, from Abraham Lincoln's head to George Washington's noggin. According to the South Bend, Indiana tire vendors, the switch raises the old test's 2/32-inch (1.6mm) or less standard to 4/32-inch (3.2mm). To justify the switch, The Tire Rack tested a 2006 Ford F-150 Super Cab 4×2. Shod with Abe-compliant rubber, the truck averaged 499.5 feet to stop from 70 miles per hour on wet pavement. The same vehicle riding on quarter-compliant tires stopped almost 122 feet (24%) shorter. We'd like to see more tests conducted using a range of rubber and vehicles in a variety of conditions performed by an organization that doesn't sell tires. Still, point taken. Is it time for tire testers to replace the penny with a quarter?
More by Robert Farago
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Please, people! It didn't stop in 122 feet. It stopped in "122 feet shorter". That means it stopped in 499-122 = 377 feet.
I rarely take tires on our vehicles down to the minimum legal limit because I routinely notice that the wet and dry traction have deteriorated enough to justify new shoes. Tires are expensive, but car wrecks are even more expensive. A few years ago I had recently put new tires on our Volvo 850. Driving in the rain a kid in his ricer dashed across the road in front of me and I was full on into the ABS braking. I missed him by about two feet. Old hard worn tires would easily have consumed that extra two fee. Tirerack has this one right, even if it is to their advantage to say so.
BTW, Bridgestone claims that many of their tire incorporate two different tread compounds in layers. The outer layer is a relatively longer wearing harder rubber while the inner layer is a softer layer with better friction characteristics. The idea is that by the time mileage and heat have done their thing the tires will be riding on that softer inner layer and loose less performance than they would if the tire used one compound for the entire tread area as most tires do. Tirerack's published test didnt' include any of these Bridgestone dual layer tires. It sure would be interesting to see that same test done with two tire models side by side, with and without the dual layer design.
Yeah I am a cheap bastard but even I have learned my lesson on driving on bald tires