Tire health ranks as one of the most important areas of car safety. However, many drivers may not know when they should opt for a new set of tires. To help make the decision a bit easier, we’ve found four examples of poor tire health that you should pay attention to.

1) Your tires failed the famous “penny test.” This is one of the best, and easiest, ways to tell if you need new tires. All you need to do is take a penny and place Lincoln upside down in the center of the tire. If you can see the top of Lincoln’s head, this means your tires have little to no tread and you need a new set.

2) You feel road vibrations. This may just be a simple matter of tire re-balancing, but if you’re still feeling lots of shaking, you're probably in need of new tires.

3) There are bubbles in the tire sidewall. Bubbles or big bulges in your tires' sidewalls usually indicate a serious internal problem. We recommend seeking immediate help about this one, as this can lead to a blowout or overall tire failure.

4) Tire “wear bars” are even with tread. Along with the penny test, your tires’ wear bars are a good indication of overall tire health. All U.S.-made tires have these bars that will start to form once your tires’ tread starts to wear down. Once you see the bars become equal with the tires’ tread, you need a replacement.