How to Change the Size of Tires

by William Zane

Your vehicle’s tires are crucial components that can affect the ride, handling and even the fuel economy. Tires are also a confusing subject, with multiple choices of brands and many different sizes and profiles. Tires are measured by three primary criteria, width, profile and diameter, all of which are printed on the sidewall of the tire. The measurements will look something like 205/65ZR-16. The first number (205) is the width expressed in millimeters, the second number (65) is sidewall, which is the distance between the wheel and the outer edge of the tire. This is a expressed as percentage of the width of the tire. A 65-series has a sidewall that is 65-percent of the width of the tire. The last number (16) is the height of the tire and wheel it is mounted on. The letter refers to the speed rating of the tire.

Step 1

Determine what size tire you want to install. This will depend in part on why you are changing the size of your tires. If you want to improve the handling and grip of your vehicle, you are likely going to install tires that are a little wider. For example, if your car has 205/50-16 tires and you want more grip, you can install a 215-width or maybe even 225-width tires. If you want better fuel economy or want to spend less, than you can go with a narrower tire. For example, you can install a 195 tire in place of a 205 tire.

Step 2

Make sure the tires will fit on your wheel. If you are only installing a wider tire, the new tires should fit on your existing wheel. However, you should not install a tire that is a lot wider than your existing tires, as it will negatively impact the vehicle’s handling. If you are installing a tire that is taller than your existing tires, you will also need to install larger wheels. For example, if you have 15-inch tires and want to install 16-inch tires, the larger tires will not fit on the 15-inch diameter wheels. You will have to install 16-inch wheels.

Step 3

Make sure the outer diameter of the tire remains the same if you want your speedometer to continue to read correctly. To make sure that the outer diameter stays the same when installing a wider tire, the side profile needs to get smaller. If you are have a 205/50-16 tire and want to install a wider tire, you can install a 215/45-16 tire. The side profile is expressed as a percentage of the width and therefore needs to be smaller as the width becomes larger in order for the outer profile to remain the same. A tire professional will be able to help you with the particular measurements on your tires.

Step 4

Buy the tires. The cheapest place to buy your tires is from a large online company that sells tires. You can order the tires and have them shipped to you and then take them to a professional and have them installed. You can also buy them locally and have the store you bought them from install them.

Step 5

Have the tires installed by a tire professional. Tires are one of those parts that cannot be installed by an amateur. Tires must be mounted on the wheels and then balanced correctly with a tire balancing machine. If the tires are not properly installed, they can wear prematurely as well as vibrate and shake when the vehicle is driven.

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