And the 15 is the size of the wheel it's designed for. So, in this case you've got a 31-inch tall tire for a 15-inch wheel. You know the wheel radius is 7.5-inches, and the tire radius is 15.5 inches.

There are two major size designations commonly used for passenger car tires, called P-metric and Metric sizing. If you see a "P" in front of the tire size displayed on a tire's sidewall it is a P ...

If you’re considering alternative fuel vehicles, you likely have an overarching question: Is it better to buy a hybrid or an electric car? Choosing the best option is your decision because ...

Runner Up: Continental ExtremeContact Sport The Michelin Pilot Sport 4S has been on our list as the top summer tire since it launched nearly three years ago. “It’s just so well balanced and ...

Few electric cars include spare tires, and manufacturers cite a wide variety of reasons — space, cost, even safety. But the main factor may be drivers who won't change a tire.