(BPT) – Cars can relay all kinds of information these days, like how many miles until you run out of gas or what’s causing that traffic jam up ahead. Your tires can offer a wealth of information, too, and knowing how to read them can help improve the performance and fuel efficiency of your vehicle.

According to the latest installment of the Hankook Tire Gauge Index, half of Americans (50 percent) don’t know what the little numbers etched into their tires’ sidewalls mean. Here are five things your tires can tell you:

1. What size do you need?

The sidewall of your tire offers information about its size, which is helpful when looking to purchase new ones. If you like how your car drives, then stick with the same size — or, if you’re considering a larger tire, you’ll know where to start. Just remember — changing the size of your tire can affect your speedometer reading, suspension and wheel wells, so be sure to thoroughly check your vehicle when installing new tires. Whatever size you’re looking for, tools like the Hankook Tire Finder can help you select the perfect fit.

2. Wheel it fit?

If you’re considering upgrading the wheels or rims on your car along with the tires, the sidewall also indicates the ideal wheel fitment size. Wheel fitment is the diameter of the tire’s rim, and a proper fit is critical for safety and performance.

3. How it’s made

Sixty-one percent of American drivers know that a tire also tells you how it’s made, according to the Gauge. The letters “R” or “B” on a tire indicate whether it’s a radial or a bias tire, meaning the tire layers are constructed in a spiral or overlap. These construction patterns provide different levels of durability for various types of vehicles. What those letters won’t tell you, however, is where the tire was made. One in five drivers (19 percent) don’t know if their vehicle was made in America — let alone their tires. However, more tires are being made in the United States as top brands like Hankook Tire open new manufacturing plants, like its new facility in Clarksville, Tenn.

4. Just the model, no pressure

Most Americans (85 percent) are aware that the sidewall gives information on the tire model. However, one important detail the sidewall does not provide is the recommended tire pressure for your vehicle, even though the Gauge found that 42 percent of drivers think it does. Look instead at the inside of the driver’s door or in the owner’s manual to determine the optimum psi for your vehicle.

5. Time to trade in

Check the tread to know when it’s time to replace your tires. There’s an easy trick to test the tread depth and determine if it’s time for new tires, and it only costs a penny. Place a penny into the groove of your tire’s tread, upside down. If Lincoln’s head is still visible, your tire is telling you it’s time for a new one.

We rely on our cars to get us to and from everyday activities, so it’s important to know what the letters and numbers on our tires indicate so we can avoid bumps in the road. Most standard tires will represent the tire type, tire width, aspect ratio, construction, rim diameter and service description, in that order, followed by a code specifying that the tire has passed the appropriate safety tests required by the Department of Transportation.