Tire Tread Depth & Road Safety: How Worn is Too Worn?
Posted Jul, 14, 2011
Buying new tires isn’t a task most of us as auto owners relish. A new set of tires can be expensive, and then there’s the hassle of scheduling an appointment at a tire shop or auto garage to have them replaced, so many drivers get as much use out of their old tires as possible. While there’s nothing wrong with trying to be efficient, many car owners rely on old tires far past their recommended use, posing a significant safety hazard to themselves and others on the road.
What’s the worst that could happen?
It’s summertime. There’s no snow or black ice on the road. So your tires are four summers old – what’s the worst thing that could happen? Well, plenty! The moment rain hits the pavement, tires with too little tread turn into ice skates; worn and bald tires have little or no ability to prevent hydroplaning, turning even the smallest puddles into danger zones.
The truth is that even when tires have some remaining tread depth, if the tread is worn, it may not be enough to provide traction during wet weather – and wet weather, as Michiganders know, is not always easy to predict! In the past few weeks alone, two cars have hydroplaned and gone off the road on the same spot on Southbound US-31 (just South of Russel Road); one of the cars hit a family in an Expedition towing a trailer as it spun off the road, rolling both the car and trailer that caused it to also catch fire. Oftentimes, it’s not only the car owner who is hurt by poor tire maintenance; innocent bystanders can be hurt too.
How worn is too worn? (the Lincoln head test)
When was the last time you looked at your car or truck’s tire tread? Tire tread should be inspected every few months – or more often, if the tires have significant wear on them already. The old way to tell if your tires still have enough tread is to use the “penny test”, or the “Lincoln head” test. Take a penny and place it upsidedown, head facing you, into the tread groove. If the tire tread only reaches to the top of Lincoln’s head (which is 2/32″), or below it, it’s time to get a new set of tires. At 2/32″, not only is wet traction essentially gone, but you also have a significantly increased dry stopping distance.
A quarter is a better measurement for true tire safety, as it measures 4/32″ of tread depth, which is the depth at which you lose wet traction. A new tire typically will have 11/32″ of tread depth, so 4/32″ is basically 1/3 of the useable tread left on the tire. Once Washington’s head shows, you know that you need to be cautious when it rains. So the short of it is that Lincoln’s head shows your tires are done, Washington’s head shows to be careful when it rains.
Other potential tire hazards.
Tires that sit dormant, especially exposed to the elements, tend to become stiff, and they may crack. Tires that feel stiff, slippery and show signs of cracking will not only provide very poor tread, but may put the driver in danger of blow outs while driving down the road.
If you’re not sure whether or not your tires still have the tread they need to provide safe transportation, stop by the shop! Our technicians would be happy to take a look and make a recommendation.
