Why The Lincoln Penny Test Still Matters

Believe it or not, the summer travel season is winding down and unofficially comes to an end this Labor Day weekend. That's when many folks will pile into their vehicles and hit the road -- bound for their favorite cottage, campground or resort town.

Today, the topic is tires and tire safety. Labor Day weekend travel aside, this is also a good time to address that subject, in light of recent industry reports indicating that, presently, 11 percent of American vehicles -- a total of 28 million cars, trucks and SUVs -- are driving around with at least one bald tire, and that 55 percent of vehicles are riding on at least one under-inflated tire.

"The fact that there are 28 million vehicles out there with at least one bald tire surprises me, and concerns me, from a safety standpoint," said Chuck Yurkovich, vice president of global technology for Cooper Tire, based in Findlay, Ohio.

"I think people in general under-estimate how important proper tire maintenance is when it comes to safety," said Yurkovich. "Remember, your tire is the only contact your vehicle has with the road. And, depending on the tire size and load, the amount of tire that's actually in contact with the road at any given moment is only slightly larger than a softball.

"You literally depend on that tire to make the vehicle stop, go, or do any kind of maneuver. The tire is your lifeline."

The dangers of driving around on a bald tire -- especially on a long trip -- are numerous:

1. Since a bald tire does not have a sufficient amount of tread, it's more susceptible to a blowout or other kinds of damage if you hit a pothole.

2. If you have a bald tire, you have less traction, and therefore less control, of your vehicle.

3. A bald tire is, by definition, an old tire. And as tires age, they're more likely to being damaged or crack on impact -- which also makes the vehicle much harder to control in an emergency situation.

Driving on an under-inflated does not pose as much of a safety risk, compared to driving on bald tire, says Yurkovich. But, if a tire is under-inflated, it makes the tire run hotter, and results in poorer fuel economy.

Here's a common misconception when it comes to proper tire pressure: Most folks think that tire pressure figure listed on the sidewall of the tire is the optimal pressure -- when in fact, that figure is the maximum pressure. To ensure your tires are inflated at the optimal pressure, follow the guidelines in your owner's manual, or on the tire sticker that can generally be found affixed to the door edge, door post, glove- box door or trunk-lid door.

Tooling around on an over-inflated tire also has many down sides: The ride quality suffers, the tire is more likely to be damaged on impact, and the section of the tire making contact with the road actually gets smaller -- which also translates to less grip, especially on a hot, dry surface.

The "Lincoln Penny" Test

Despite all of the advancements in tire design and technology over the last 20 years or more, the "Lincoln penny" test is still recommended, says Yurkovich, as the best way to determine whether you still have enough tread left -- or whether it's time to buy new tires and send "old baldy" to the landfill.

For those who don't recall this time-honored method: Insert the edge of the penny into the tread upside down. That is, with the top of Honest Abe's noggin going in first. If the top of Lincoln's head is covered by tread, that means you still have an acceptable and safe amount of tread. Do this test at various points around the perimeter of the tire. If the top of his Lincoln's head is visible at any point around the tire, the tire is ready for the recycling center -- and it's time for you to go tire shopping.

And, while you're doing the penny test, also look for signs of uneven wear or damage such as cuts, cracks, splits, punctures and bulges, advises Yurkovich. Any of these can significantly shorten the tire's life span -- and if they're not corrected, more damage or less of pressure can occur.

And with the unofficial end of summer looming, August is a good time to go tire shopping, especially for those who are hitting the road for the Labor Day weekend. It's especially true for those in Northern climes. Because, before you know it, November will be here, the first snowfall will hit, and the tire stores will be jammed with folks looking to replace their old, worn tires.

"Yes, if you wait for the first snow, that's when everyone in the world wants new tires, so the tire stores often run out," confirms Yurkovich. "So, if you inspect your tires now, and do a maintenance check, and replace what needs to be replaced, you'll avoid the panic of having to find something at the last minute when the roads are covered with snow."

Replace All Four Tires

It's never a good idea to replace just one tire. If you have a brand new tire on one wheel, and older, more worn tires on the other three wheels, that will result in your vehicle pulling in one direction or the other, and cause an imbalance in traction.

Ideally, you should replace all four tires at once. But if you're on a budget, and can only replace two, put the new ones in the rear. "That will give you the most control," advises Yurkovich -- "even if your vehicle has front-wheel drive."