How to Choose Tires for Your Car

by Jody L. Campbell

Choosing tires for your car can get confusing if you want to upgrade to an alternate tire size and performance. A rule of thumb with most reputable tire dealers is that you should never go down in tire variables, but you can always go up. For example, if the car's recommended tire from the manufacturer indicates a designated speed rating, you can purchase an aftermarket tire with a higher speed rating, but don't buy one with a lower speed rating.

Locate the tire label for your car. It is most likely in the driver's side door frame or on the driver's side door itself. Other possible locations would be a label in the glove box. Some Fords place it in the passenger rear door frame. This label will give you all the information about the tires that the manufacturer recommends, including size, suggested air pressure, speed rating, load capacity and any alternate tire sizes that would also work on your car.

Write down the information on the tire label on a piece of paper.

Decode the information. For example, P 185/65 R15 88H would be deciphered in this way: P stands for the tire type, in this case a "passenger" rated tire. The 185 is the width of the tire in millimeters measured from the bottom of the bead on one sidewall to the other. The 65 means that the aspect ratio of the tire's sidewall is 65 percent of the tire's width. The R stands for "radial." The 15 is the diameter of the tire in inches. The 88 is the load ratio for the specific tire; in this case 88 would indicate the tire can maintain up to 1,235 pounds. The H is the speed rating for the tire; in this case, an H-rated tire is designed to endure speeds up to 130 miles per hour. Refer to the chart in Resources for all conversions.

Determine what you want new tires for. If it's just to replace the ones you have due to age and or normal wear and tear, tire dealers and dealerships will recommend that you replace the tires based on the tire label of your car. Those specific sized tires were measured and considered for your car when it was manufactured. You can increase load, speed rating and even size, but it would be recommended to have a tire dealer or dealership measure and convert your tire size before buying and installing them. Buying a taller tire will manipulate your odometer and speedometer readings. Increasing tire height and width can cause the tire to rub on the inner fender well when making turns.

If you do not care about any specific design or look or performance, stick with the tire label and purchase the recommended tires for your car.

If you're looking for increased load range (for light or regular trucks) or an increased speed rating, or you want to fill the tire well up with a taller, wider tire, check with a tire dealer or dealership to see what your options are for that vehicle. Many reputable tire dealers will have a measurement conversion chart that can show you how to manipulate tire height and width based on the designated tire size for the vehicle without compromising the load or speed rating of the tire.

About the Author

Jody L. Campbell spent over 15 years as both a manager and an under-car specialist in the automotive repair industry. Prior to that, he managed two different restaurants for over 15 years. Campbell began his professional writing career in 2004 with the publication of his first book.