What does 315/45R21 mean?
315/45R21 is a tire size with the following dimensions:
- 315 is the width of the tire in millimeters. This number also indicates the appropriate width of the rim on which the tire should be mounted.
- 45 is the aspect ratio, which is the ratio of the tire's height to its width. This affects the tire's handling and ride comfort
- R indicates the tire's construction type, meaning it has a radial construction. This provides stability and precision to the tire.
- 21 is the diameter of the wheel in inches, on which the tire is to be mounted.
315/45R21 Tire Conversion
| Dimensions | Inches | Millimeters |
| Tire Diameter | 32.2 in | 816.9 mm |
| Section Width | 12.4 in | 315 mm |
| Rim Height | 21 in | 533 mm |
| Sidewall Height | 5.6 in | 141.8 mm |
| Circumference | 101 in | 2566.4 mm |
| Revolutions | 627.1 revs/mile | |
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FAQ About 315/45R21 Tire
How tall is a 315/45R21 tire?
The height (or diameter) of a 315/45R21 tire is 32.2 inches
How wide is a 315/45R21 tire?
The width of a 315/45R21 tire is 315 mm, which is about 12.4 inches.
What size rim fits a 315/45R21 tire?
A 315/45R21 tire fits on a rim that is 21 inches in diameter.
What does the 45 in a 315/45R21 tire mean?
The 45 in a 315/45R21 tire refers to the aspect ratio, meaning the height of the tire's sidewall is 45% of its width.
Alternative Tire Sizes for 315/45R21
Typically, it's recommended to choose a tire with a diameter (height) within 3% of the original equipment manufacturer (OEM) tire size.
However, keep in mind that this is a general guideline and not an absolute rule.
Here are some tire sizes that are compatible with the 315/45R21:
| Tire Size | Diameter | Rim |
|---|---|---|
| 275/50R21 | 31.8″ (-1.2%) | 21 x 7.5-9.5 |
| 275/55R21 | 32.9″ (2.2%) | 21 x 7.5-9.5 |