- 1). Read the owner's manual of your vehicle to find the recommended rim, or wheel, size. It's important to know the specific size and style of rim your vehicle was meant to have when preparing to size and purchase rims.
- 2). Remove the tire from the rim and measure the diameter of the bead of the tire, which is the official rim size. The tire bead is the inner edge of the tire that sits on the rim. Your measurement should result in a whole number, such as 15 or 16 inches.
- 3). Look at the "size series" printed on the the tire, which should show you the appropriate rim size. The "size series" is a series of numbers that usually begins with a P, for passenger, or LT, for truck.
For example: "P200/80/R17" or "LT210/70/R18"
In the above examples the number after the R represents the rim size in inches. What the R actually stands for is "radial tire." - 4). To measure the size of an unmarked rim, use your tape measure and take a measurement of the diameter of the rim. The diameter of the rim goes from one edge of the rim through the middle of the rim and straight across to the other side. Rims come in whole inch increments, so your measurement should be a whole inch, such as 15 or 16 inches.
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