How do I know what rim size?
You can usually determine rim size by checking the tire sidewall, the vehicle's door placard, and the wheel itself. The most common rim size is the diameter shown after the letter “R” in the tire size, measured in inches. Confirm with official documentation if needed.
Where to find rim size and how to read it
The following steps guide you to identify the correct rim size. The list explains where to look and how to interpret the numbers.
- Check the tire sidewall for the size code, such as P215/60R16. The number after the “R” (in this example, 16) is the rim diameter in inches.
- Inspect the vehicle’s door jamb placard (or the owner’s manual) for the recommended rim size, bolt pattern, and offset for your model.
- Look at the wheel itself; many rims have stamped markings like “6.0Jx16” or “16x7,” which indicate diameter and width in inches.
- If you cannot find a clear marking, measure the wheel’s bead seat diameter (BSD) once the tire is removed; for most passenger cars, BSD equals the rim diameter in inches.
Concluding note: Cross-checking the tire size, wheel markings, and vehicle documentation helps ensure you identify the correct rim size and avoid fitment issues.
Understanding rim size beyond the diameter
Rim size is not only about diameter. Compatibility also depends on width, bolt pattern, center bore, offset, and clearance with brakes and suspension. The following sections break down what to verify when selecting or replacing rims.
What the numbers mean on rims and tires
Common markings include:
- Diameter (the overall wheel diameter in inches, e.g., 16, 17, 18).
- Width (how wide the wheel is, often listed as a number like 6.5, 7.0, 7.5 inches, sometimes followed by a “J” to indicate flange shape).
- Offset (ET value, measured in millimeters, indicating how far the wheel sits in relation to the hub).
- Bolt pattern (PCD), such as 5x114.3 mm, which must match your hubs.
Key compatibility factors to verify before upgrading
Before buying new rims, confirm:
- The bolt pattern (PCD) matches your hub.
- The center bore size accommodates the hub without remaining play.
- The width is within the tire’s acceptable range for the chosen tire size, to maintain correct sidewall height and handling.
- The offset (ET) clears brake calipers, suspension components, and fenders.
- The overall load rating and speed rating meet or exceed the vehicle’s requirements.
Summary
To know your rim size, start with the tire size on the sidewall—the number after the “R” is the rim diameter in inches—then confirm with the vehicle’s door placard or owner’s manual. Check the wheel markings for diameter and width, and consider bolt pattern, center bore, offset, and clearance with braking components when selecting rims. When in doubt, consult a professional to ensure proper fit and safe operation.
