1. High risk of hydroplaning. Today’s tires are designed with deep grooves in the tread patterns that channel water away from the tire on wet roads. As the tread wears away over time, these grooves become shallower and lose their ability to effectively displace the water under the tire. This can result in hydroplaning, where the tires can no longer grip the road and the car can easily skid out of control.
2. Weak “grip” on snow and ice. Most tires are also designed with “sipes,” which are small, thin grooves or channels cut into the tire that help improve traction when driving on snow. As the tire tread makes contact with the pavement, the sipes expand, creating an area of lower air pressure inside the cuts that provides more reliable contact between the tire and the surface of the road. As the tread on a tire wears away, so do the snipes, reducing the traction and making it more likely lose control on snow and ice.
3. Excess heat buildup. Driving creates a lot of friction between your tires and the surface of the road, and as we all know, friction creates heat. Tire manufacturers minimize the amount of heat by designing grooves in the treads, which helps to cool tires by allowing air to flow in between. When the grooves are worn, the airflow declines and the tire heats up, making it more susceptible to failure. Low tire tread also means less grip on the road.
4. More prone to sudden blowouts. The thick tread on new tires can’t prevent all punctures, but it greatly reduces the chances of having a blowout. Conversely, tires with very little thread offer no protection to the tire casing. As a result, nails, pieces of glass, or other debris on the road can easily puncture the tire, causing a blowout and loss of control of the vehicle, especially at high speeds.
5. Air leakage. Worn tires are more likely to lose air pressure, which can lead to a variety of problems. Underinflated tires can’t grip the road properly, and can negatively impact steering and braking. They reduce gas mileage and drive up gasoline costs. And they cause the tread to wear out quicker, which means you have to replace them sooner than expected.
When to Rotate Your Tires
One of the best ways to prevent early or uneven tread wear is to rotate your tires on a regular basis. How often can vary depending on a number of factors, including how much you drive, the road conditions in your area, and the weather.
When you purchase a set of tires, the retailer will provide a recommended schedule for tire rotation. In addition, most will provide the service at no charge, as this helps prevent uneven wear on the tires, making it more likely they will achieve the expected lifetime mileage. At a minimum, most tire manufacturers recommend rotating your tires at least every six months or 7,500 miles, whichever comes first. Another good technique is to rotate your tires every time you change the engine oil.
When to Replace your Tires
No matter how carefully you drive or how often you rotate them, your tires will eventually wear out and need replacing. When this occurs will depend on the brand and quality of the tire, as well as your driving habits. Regardless of how many miles you have on the tires, if you spot any of the following it’s time to replace them:
• Insufficient tread depth. If the remaining tread on your tires is less than 1/16 of an inch, it’s time for new tires. You can buy a tire tread gauge and measure the depth of your treads once a month. Or, place a Lincoln-head penny into the tread with the “heads” side facing you. If you can see all of Lincoln’s head, it means your tread has worn too thin for safe driving.
• Easily visible tread wear indicator bars. Today’s tires come with a convenient feature – tread indicator bars – that also helps to determine tread safety. These consist of flat rubber “bars” that are built right into the tire. On new tires, the bars can’t be seen. Over time, as the tread wears away, they become easier to see. When you can clearly see one or more of these indicator bars, it time’s for new tires.
• Cracks in the sidewall. Worn treads aren’t the only sign that you need new tires. Older tires can also develop cracks or cuts in the sidewall that can compromise the structural integrity of the tire. Most tires will have very small cracks or cuts that require close inspection to be seen. But when they become obvious, it’s a sure sign of a distressed tire that needs replacement.
• Bulges and blisters. Sometimes tires can develop bulges and blisters on the surface without causing overt cracks. These can cause weak spots that increase the chances of a sudden blowout. They can also interfere with the tire’s ability to properly grip the road, thereby increasing the risk of hydroplaning or losing control of the car.
• Too much vibration. Excessive vibration can come from many different sources, including misalignment, unbalanced tires and more. It can also indicate structural problems with the tires that make them unsafe to drive. If your car vibrates too much while driving, have an experienced auto technician examine the tires for signs of damage.
So why take a chance? Worn tires put everyone at risk but making it easier to lose control of your car when you least expect it. Replacing worn tires before they cause an accident will make driving safer for you and everyone else on the road.