While most vehicle owner manuals suggest changing your tires roughly every 30,000 miles, a tire's life is influenced by a number of different factors.
Tires that spend lots of time in warmer environments tend to age faster. This is especially true in a hot climate. Certain environmental factors, such as exposure to coastal climates and excessive sunlight, can speed up the aging process and shorten the life of the tires. It stands to reason that tires on vehicles stored outdoors won't last as long as tires on vehicles stored inside a garage.
The conditions of the roads you regularly drive on each day play a big role in how quickly your tires wear out. For example, if your daily drive happens mostly on smooth asphalt with the occasional pothole, then the wear and tear your tires see is significantly less than someone who loves off-roading and navigating rocky paths and trails.
Do you like to ride on the shoulder? Do you tend to hit the curb often? Do you take turns and corners faster than most people? How you drive your vehicle plays a big part in the amount of stress your tires are put under. Drive your vehicle harder and your tires will wear out more quickly. Drive more conservatively and they'll generally last much longer.
Perhaps the clearest sign that you need new tires is a lack of tread. You can easily check your tire tread with just a penny, but there's also an indicator built into most modern tires. Indicator bars (sometimes called wear bars) are found in between the treads and are there to help you determine if it's time for fresh tires. If the tread is flush with the indicator bar, it's time for a replacement.
Another simple way to check the age of a specific tire is to check the sidewall. No matter the manufacturer, the last Tire Identification Number (TIN) will always begin with the letters DOT. This means the tire meets all industry standards and has been approved by the Department of Transportation for safe use. The last 4 digits of every TIN will always tell you the week and the year the tire was made. The first 2 digits are the number of weeks into the year in which the tire was made. The last 2 digits represent the year. So if a tire has a sidewall number that reads DOT BF 4G ABCD 3218, then you know the tire was made in the 32nd week of the year 2018.
If the sidewall of your tires is cracked or has any unusual grooves then it's a clear sign that your tires have aged and need to be changed. Additionally, if there are any bubbles or blister-like bumps on the tire, then the tire is at risk of being blown out and causing further damage to your wheels.
If something sounds or feels slightly off – it probably is. If you start experiencing excessive noise in the cab while driving or if you feel a vibration or shaking in the wheels, then it's time to have your tires inspected. You probably just need the tires balanced or aligned, but there's a chance they could be coming to the end of their life.
Under-inflated or overinflated tires not only decrease the life expectancy of your tires, but also help with performance, fuel efficiency, and handling.
This goes further than just making sure you still have adequate tread left on your tires. Turn your steering wheel all the way to one side and take a close look at both sides of the tire. If the tread is more worn on one specific side, then your tires may be misaligned. This will shorten the overall lifespan of the tires and should be corrected immediately to make sure your tires last as long as possible.
By regularly rotating your tires, you're more evenly distributing the natural wear and tear. A good rule of thumb is to have your tires rotated each time you have your oil changed.