285/45R21
A 285/45R21 tire is 31.10 inches tall and 11.2 inches wide, with a 5.05-inch sidewall, mounted on a 21-inch wheel.
Overall diameter
31.10″
790 mm
Sidewall height
5.05″
128.3 mm
Tread width
285 mm
11.2″
Circumference
97.70″
8.1 ft
Revs per mile
649
403 per km
Wheel diameter
21″
aspect ratio 45%
Cross-section
- Overall diameter
- 31.10″
- Sidewall (each side)
- 5.05″
- Wheel
- 21″
285/45R21 in inches and millimeters
Every dimension of a 285/45R21, converted both ways. Calculated from the size code, accurate to about 1%.
| Measurement | Inches | Millimeters |
|---|---|---|
| Overall diameter (height) | 31.10″ | 790 mm |
| Tread width | 11.2″ | 285 mm |
| Sidewall height | 5.05″ | 128.3 mm |
| Wheel diameter | 21″ | 533 mm |
| Circumference | 97.70″ | 2482 mm |
Nominal dimensions from the size code. A real tire varies by a few millimeters between manufacturers, and a loaded tire sits slightly shorter than its free diameter.
285/45R21 compared with other sizes
All 26 practical swaps involving 285/45R21 — diameter change, speedometer impact and a fit verdict for each.
285/45R21 → 255/60R19
255/60R19
Diameter +0.2% · This fits
285/45R21 → 275/55R19
275/55R19
Diameter +0.6% · This fits
285/45R21 → 255/55R20
255/55R20
Diameter +0.2% · This fits
285/45R21 → 265/55R20
265/55R20
Diameter −1.2% · This fits
285/45R21 → 285/50R20
285/50R20
Diameter −0.4% · This fits
285/45R21 → 265/45R21
265/45R21
Diameter +2.3% · This fits
285/45R21 → 275/45R21
275/45R21
Diameter +1.2% · This fits
285/45R21 → 275/50R21
275/50R21
Diameter −2.3% · This fits
285/45R21 → 285/40R21
285/40R21
Diameter +3.7% · Borderline. Check clearance first
275/45R21 → 285/45R21
275/45R21
Diameter −1.1% · This fits
265/45R21 → 285/45R21
265/45R21
Diameter −2.3% · This fits
275/50R21 → 285/45R21
275/50R21
Diameter +2.3% · This fits
285/40R21 → 285/45R21
285/40R21
Diameter −3.6% · Borderline. Check clearance first
285/50R20 → 285/45R21
285/50R20
Diameter +0.4% · This fits
285/40R22 → 285/45R21
285/40R22
Diameter −0.4% · This fits
255/60R19 → 285/45R21
255/60R19
Diameter −0.2% · This fits
255/55R20 → 285/45R21
255/55R20
Diameter −0.2% · This fits
275/55R19 → 285/45R21
275/55R19
Diameter −0.6% · This fits
265/55R20 → 285/45R21
265/55R20
Diameter +1.2% · This fits
275/40R22 → 285/45R21
275/40R22
Diameter −1.4% · This fits
285/45R22 → 285/45R21
285/45R22
Diameter +3.2% · Borderline. Check clearance first
265/55R19 → 285/45R21
265/55R19
Diameter −2.0% · This fits
265/50R20 → 285/45R21
265/50R20
Diameter −2.1% · This fits
285/45R21 → 275/40R22
275/40R22
Diameter +1.4% · This fits
285/45R21 → 285/40R22
285/40R22
Diameter +0.4% · This fits
285/45R21 → 285/45R22
285/45R22
Diameter −3.1% · Borderline. Check clearance first
Common questions
- What is 285/45R21 in inches?
- A 285/45R21 tire is 31.10 inches tall and 11.2 inches wide, with a 5.05-inch sidewall, mounted on a 21-inch wheel. In metric that is 790 mm tall and 285 mm wide. The circumference is 97.70 inches.
- How tall is a 285/45R21 tire?
- 31.10 inches, or 790 mm. That is the overall diameter, wheel included. It turns about 649 times per mile, which is what your speedometer counts.
- What do the numbers in 285/45R21 mean?
- 285 is the tread width in millimeters, 45 is the aspect ratio — the sidewall height as a percentage of the tread width — and 21 is the wheel diameter in inches. So the sidewall is 285 × 45% = 128.3 mm tall.