Auto Tire Safety
Have you ever heard of a tire test called “The Lincoln penny tread depth test” It sounds crazy, but it works! For years it has been deemed a suitable method of determining when you need to replace your tires. It's based on the premise you're driving on legal tread depths anytime the top of Lincoln's head is hidden by the tread and that a tire's ability to grip the road isn't greatly affected in bad weather conditions, such as rain, slush and snow. When the tread wears to about 2/32" of remaining depth, you're ready for new tires. At this time, at 2/32", you can see the penny above Lincoln's head. Although this is a fun test, we wouldn’t recommend just going by Lincoln!
Your ability to control your vehicle depends on the traction between your tires and the road. Tires don't require tread designs or even much tread depth to deliver traction on a dry road. A practical example of this is the racing slicks used on stock cars and open-wheel racers that provide traction at over 200 mph. However, tires do require significant treads to acquire traction on wet, slushy and snow-covered roads. Liquids can't be compressed and require time and energy to move them out of the way as our tires drive through them. Those same racing slicks would lose traction at really slow speeds anytime something prevented them from maintaining constant contact with the road surface.
So a good solid tread is necessary to direct water and slush from between the tire and the road, as well as provide edge that bites into the snow. But that only solves half the problem that tread depth contributes to how well the tread does its job. Amount of air is the other factor.
The huge amounts of air (wind) our tires encounter at highway speeds can easily be compressed and moved out of the way with ease. However the same isn't true of liquids. When water collects on the road during a heavy rain, the depth of the water, vehicle speed and how heavy your car or truck is, as well as the tires' tread designs and tread depths together determine when and if the tires will be forced to hydroplane and how quickly they can stop a vehicle.
A typical passenger car tire has about twenty square inches of total footprint surface and begins with about 1/3" of tread depth. While the majority of the footprint surface is made up of the rubber that grips the road, the remainder is the empty space of the grooves that make up the tread design. The tread will wear away slowly over the life of the tire and the tread grooves will increase. So don’t wait until Lincoln’s head is slipping out of view! Check your tire treads regularly to avoid an accident or a tire blow out!
In winter, when snow-covered roads are a concern, you should consider replacing your tires when they reach approximately 5/32" of remaining tread depth to maintain good traction. Those of us in cold climates need more tread depth in snow because your tires need to squish the snow in their grooves and then “let it go” (think Disney) as they roll. If there isn't enough tread depth, the "bites" your tires can take on each revolution will be reduced and your car may lose traction. Gordon Tower Insurance wants to help you stay safe and keep your auto safe too!