How to Tell What Size Tires Fit Rims

Getting the tire that will fit the rim you're putting it on is easy once you know what measurements to take of the rim and how to read tire size specifications. If you're not sure what kind of tire to get for your vehicle after sizing, the owner's manual will specify what kind of tire and what size rims you should use.

Things You'll Need

• Tape measure

Instructions

1. On the back of the rim, measure the distance from one edge to the opposite edge. This will give you the rim's diameter.

2. Measure the distance between the flanges of the rim. The flanges are the part of the rim that the tire beads actually come in contact with. This measurement is rim width.

3. Measure the bolt pattern. For four-lug rims, measure the distance from the center of one hole to the center of the hole on the opposite side. For five-lug start at the center of one hole, skip the next hole and measure the distance to the center of the third hole. Six-lug and eight-lug rims can be measured using the same process as four-lug rims.

4. Match tires that meet your rim's measurements. Specifications will list tire size in a series of letters and numbers. The first value in a tire's size will be a letter, depending on the type of tire. You'll commonly see "M+S" for mud and snow and "P" for passenger. The first number is the tire width in millimeters. The width will be followed by a slash. The number after the slash is the tire's aspect ratio, which is the ratio of the tire's height to its width. After the aspect ratio number, there will be another letter. This will denote the type of tire: "R" for radial tires, "B" for belted bias tires and "D" for bias ply tires. The last number will be the inside diameter in inches, which is the number you match to the rim diameter. For example, P175/65R14 tells you that this tire is designed for passenger vehicles, is 175 mm wide, its height is 65 percent of its width, it's a radial tire, and the rim size is 14 inches.

Tips & Warnings

• The same size notation that will be on a tire specification list at a store can often be found on the side of the tire as well.

References

• National Highway Traffic Safety Administration: Tire Safety
• Tirerack: Tire Size Information
• MRT: How to Measure Bolt Pattern

Resources

• Read this Article in Spanish